Lincoln Shield Cent Errors & Varieties Guide (2010–2025)

The Lincoln Shield Cent, introduced in 2010 after the four-part 2009 Bicentennial series, is the current and permanent chapter of America’s longest-running coin design. Its Union Shield reverse — created by Lyndall Bass and sculpted by Joseph Menna — combined with the copper-plated zinc planchet in use since 1982, produces an error profile unlike any previous Lincoln cent era. Two forces define it: Single-Squeeze Hubbing, which eliminated rotational doubling and replaced it with subtle Class IX central doubling on the date, ear, bowtie, and inscriptions; and the galvanic vulnerability of the zinc-copper planchet, which generates non-error plating defects (blisters, zinc rot) that routinely mislead beginners. This guide catalogs every documented error and variety across both eras of the Shield Cent series — 15+ anomalies from trophy-class doubled dies worth hundreds of dollars to the common die chips found in pocket change. For year-by-year values of standard Lincoln cents, see our complete Lincoln Penny value guide.

Lincoln Shield Cent Error Values & Price Guide

The master reference table below covers every documented error and variety in the Lincoln Shield Cent series, grouped by tier. Values represent typical certified (PCGS/NGC) auction and retail prices in MS65–66 Red unless otherwise noted, as of early 2025. Error name links jump to detailed identification sections further below; Year/Mint links open dedicated year-error subpages.

Values represent typical certified (PCGS/NGC) auction prices as of early 2025. Raw, circulated examples of die varieties typically trade at 20–40% of certified Mint State values. For standard Lincoln cent values by year and mint, see our complete Lincoln Penny value guide.

How to Identify Lincoln Shield Cent Errors

Required Tools

• 10x–20x Loupe: Essential for all doubled die identification. A 10x loupe is the minimum; 20x helps confirm notching on letter serifs. The 2014 DDO FS-101 is the only Shield Cent variety potentially visible without magnification.
• Digital Scale (0.01g precision): Useful for confirming correct weight (2.50g). Any significant deviation from 2.50g may indicate a broadstrike (expanded and lighter) or a wrong-planchet issue.
• Oblique LED or Halogen Light: Angled light reveals die cracks, die chip edges, and surface texture differences — critical for separating plating blisters from die-struck anomalies.

Composition & Era Reference

Step-by-Step Inspection Workflow

1. Step 1 — Year and Mint: Identify the year and mint mark first. Before 2017, Philadelphia cents have NO mint mark. Starting in 2017, they bear a small “P.” All major doubled die varieties are Philadelphia issues. Key hunting years: 2014 (DDO FS-101), 2017 (Doubled Ear), 2023 (Extra V), 2015 (DDO WDDO-006).
2. Step 2 — Examine the Date Under Magnification: Under 10x–20x, look at the date digits. Does any thickening appear ROUNDED and RAISED (genuine DDO) or FLAT and SHELF-LIKE (worthless Machine Doubling)? For 2014, the digit “4” is the primary target.
3. Step 3 — Inspect LIBERTY for Notching: The definitive fingerprint of a genuine Shield Cent doubled die is NOTCHED SERIFS — split letter corners, especially on “B,” “E,” and “R.” Machine Doubling never produces notching.
4. Step 4 — Check IN GOD WE TRUST: Class IX doubling concentrates thickening on the central motto. Look for rounded extra thickness across the letters, not flat shelving.
5. Step 5 — Lincoln’s Ear (2017-P Only): Check the earlobe for a distinct secondary curved lobe protruding directly below the primary — the 2017 Doubled Ear FS-101.
6. Step 6 — VDB Initials Area (2023-P Only): Examine below the shoulder truncation for a raised V-shaped element adjacent to the V.D.B. initials.
7. Step 7 — Scan the Entire Rim: On both obverse and reverse, check for cuds — raised featureless blobs touching the rim ($20–$100+). The Shield reverse’s intricate lines are especially prone to die breaks.
8. Step 8 — Lincoln’s Mouth (2019+ Dates): Look for a raised linear die crack extending downward from the mouth — the “Spitting Lincoln” novelty error ($5–$20).
9. Step 9 — Identify Plating Defects: A raised rounded dome with smooth luster over it = plating blister (no value). A dark, powdery, or crumbling gray area = zinc rot (damage). Neither is a mint error.

Hub Doubling vs. Machine Doubling on Lincoln Shield Cent lettering: rounded raised extra thickness with notched serifs (genuine DDO, left) vs. flat shelf-like displacement that thins letters (Machine Doubling, right)

Plating Blister vs. Die Chip: hollow rounded dome with smooth luster continuity and no sharp edges (no value, left) vs. solid jagged raised metal fragment with irregular sharp boundaries (die chip, right)

Most Valuable Lincoln Shield Cent Errors

The three trophy-class errors of the Lincoln Shield Cent series are verifiable, attributed by PCGS and NGC, and command significant certified premiums — particularly in high Mint State grades with full Red color designation. Each is exclusive to the Philadelphia (P) mint and arises from the single-squeeze hubbing process’s distinctive Class IX (central) doubling mechanism, with the exception of the 2023 Extra V, which is a die-state anomaly near the designer’s initials.

2014-P DDO FS-101 — “The King”

The 2014-P DDO FS-101 is the premier die variety of the entire Lincoln Shield Cent series and the unanimous benchmark against which all modern cent doubled dies are measured. Nicknamed “The King,” it is the only Shield Cent variety potentially visible to the naked eye by a trained observer, making it the highest-priority target for roll searchers focusing on the 2010–present era. It carries three attribution codes recognized by major grading services: FS-101 (Cherrypickers’ Guide), WDDO-001 (Wexler’s Die Varieties), and CONECA 1-O-VI.

2014-P DDO FS-101 “The King”: the digit “4” dramatically widened and distorted (red circle), and notched split serifs on “B,” “E,” and “R” in LIBERTY (yellow arrows) — the premier doubled die of the Lincoln Shield series

Pickup Points

1. The Date “2014” — Primary Diagnostic: The entire date exhibits strong extra thickness. The digit “4” is particularly widened and distorted — this single pickup point is the most dramatic in the entire Shield Cent series and the first place to look.
2. LIBERTY — Letters “BER”: Distinct notching (split serifs) on the bottom serifs of “B,” “E,” and “R.” The “L” is significantly thickened.
3. IN GOD WE TRUST: Moderate thickening is visible across the motto, though less dramatic than the date and LIBERTY.
4. Die Markers (Late Die State): Some later die states exhibit a die crack on the reverse Shield near the upper left quadrant — useful for confirming die attribution when doubling is less pronounced due to die wear.

Values & Auction Records

• MS65–66 Red:$250–$450 — typical certified auction range at GreatCollections and Heritage
• MS67 Red: Significantly higher due to condition rarity

See the PCGS CoinFacts page for the 2014 DDO FS-101 for full population data and price history. For attribution diagnostics, see Variety Vista — 2014-P DDO-001. A certified MS-67 Red example is documented at GreatCollections (lot 1286852).

For the complete 2014 error guide, see 2014 Lincoln Cent Errors.

2017-P Doubled Ear FS-101

The 2017-P Doubled Ear FS-101 is a banner variety that draws direct comparison to the iconic 1984 and 1997 doubled ear cents — two of the most popular Lincoln cent varieties in American numismatics. The 2017 date carries the additional distinction of being the first year Philadelphia cents bore a “P” mint mark since 1942, adding type-collection appeal. MS65 examples trade reliably in the $50–$100 range, making this a highly liquid variety at multiple price points.

2017-P Doubled Ear FS-101: a distinct secondary earlobe curves below the primary — the secondary lobe replicates the geometric curve of ear anatomy rather than appearing as an amorphous blob

Pickup Points

1. Lincoln’s Ear — Primary Diagnostic: A distinct, second earlobe protruding directly below the main lobe. It appears as a sharp, curved line or “dropped” lobe that replicates the exact geometric curve of the ear anatomy. This is the definitive pickup point.
2. LIBERTY: Some extra thickening may also be visible on the letters, though the ear is the key diagnostic.
3. Die Markers (Late Die State): Late die states of this variety show a die crack on the reverse running through the “M” in AMERICA — useful for confirming attribution on worn specimens.

Values & Auction Records

• MS65:$50–$100
• MS65–66 Red:$300–$500
• MS67+:$655 (documented auction record, PCGS Auction Prices)

Attribution reference: Wexler’s Die Varieties — 2017-P DDO listings.

For the complete 2017 error guide, see 2017 Lincoln Cent Errors.

2023-P “Extra V” VDB Variety

The 2023-P “Extra V” is the most recently discovered significant variety in the Shield Cent series and is currently the most actively traded modern cent novelty in the collector market. A raised element resembling an extra letter “V” appears near the V.D.B. designer’s initials below Lincoln’s shoulder truncation. The variety has been authenticated by major grading services (PCGS and NGC). As a recent issue, unsearched rolls remain widely available — making this an unusually accessible trophy-tier target for contemporary roll hunters.

2023-P “Extra V” VDB Variety: raised V-shaped element (red circle) adjacent to the V.D.B. designer’s initials below Lincoln’s shoulder truncation — authenticated by PCGS and NGC

Pickup Points

1. Location: Below the truncation of Lincoln’s shoulder, specifically near the V.D.B. designer’s initials.
2. The Anomaly: A raised element that bears a striking resemblance to an extra letter “V” adjacent to or essentially overlapping the existing initials. Must be a consistent, well-defined, raised feature.
3. Authentication Standard: This variety has been confirmed as consistent and repeatable across multiple specimens by PCGS and NGC — distinguishing it from random zinc corrosion or die gouges in the same area.

Values & Auction Records

• Raw examples:$20–$40
• Certified MS66: approximately $150
• Certified MS66 range:$120–$160

For the complete 2023 error guide, see 2023 Lincoln Cent Errors.

Lincoln Shield Cent Doubled Dies & Findable Varieties

Beyond the three trophy errors, the Lincoln Shield Cent series offers four additional FS-numbered or WDDO-listed doubled die varieties that are realistically findable in bank rolls, plus a diverse landscape of die failure errors discoverable in circulation. All Class IX doubled dies below manifest as rounded extra thickness concentrated on the date, LIBERTY, and IN GOD WE TRUST — the characteristic signature of single-squeeze hubbing. A 10x loupe is required for all of these.

2015-P DDO WDDO-006 (FS-101)

The 2015-P DDO WDDO-006 is the most consistently overlooked “Best Of” variety in the Shield Cent series. Specialists note it offers strong diagnostic presence — clear separation and notching with a definitive Southeast spread — at a price point well below the flagship 2014 and 2017 varieties. Its NGC VP-001 designation facilitates attribution by both major grading services. See Numismatic News’ original report on the 2015-P doubled die discovery.

2015-P DDO WDDO-006: Southeast spread on date digits with notched lower serifs on “B,” “E,” and “R” in LIBERTY, and distortion on IN GOD WE TRUST that progressively increases left to right

Pickup Points

1. Date “2015”: Clear separation and notching on the bottom of all digits. The spread direction is to the Southeast.
2. LIBERTY: Notching on the lower serifs of “B,” “E,” and “R.”
3. IN GOD WE TRUST: Distortion that progressively increases from left to right across the motto — a distinctive attribute of this die.

Values

• MS65–66 Red:$45–$100

For the complete 2015 error guide, see 2015 Lincoln Cent Errors.

2011-P DDO FS-101 (WDDO-001)

The 2011-P DDO FS-101 is among the first FS-numbered doubled die varieties of the Shield Cent series to achieve broad market recognition. It is a textbook Class IX (central) doubling specimen — concentrating its thickening on the central inscriptions as predicted by single-squeeze hubbing theory.

2011-P DDO FS-101 and 2010-P DDO FS-101 comparison: Class IX central doubling showing rounded extra thickness on LIBERTY and IN GOD WE TRUST, with notched letter corners confirming genuine hub doubling rather than machine doubling

Pickup Points

1. LIBERTY: Strong extra thickness visible under 10x loupe — the primary diagnostic target.
2. IN GOD WE TRUST: Thickened and distorted lettering concentrated in the central design area. The date and bowtie may also show Class IX distortion.

Values

• MS65–66 Red:$30–$70

For the complete 2011 error guide, see 2011 Lincoln Cent Errors.

2010-P DDO FS-101 (WDDO-001)

The 2010-P DDO FS-101 holds the distinction of being the first documented doubled die variety of the Lincoln Shield series — a historically significant attribute that adds collector appeal beyond the variety’s diagnostic merits alone. First-year-of-issue designation is a recognized desirability factor in the certified market. Reference: Wexler’s Die Varieties — 2010-P DDO catalog.

Pickup Points

1. LIBERTY: Thickening on the entire word, with the defining pickup being notched corners — split serifs specifically on letters “E,” “R,” “T,” and “Y.”
2. Differentiation Note: First-year dies experienced high production stress. Only coins showing defined notching at letter corners qualify as genuine DDO — mushy, shapeless expansion without notching is die deterioration doubling, not a variety.

Values

• MS65–66 Red:$25–$50

For the complete 2010 error guide, see 2010 Lincoln Cent Errors.

2018-P DDO WDDO-001

The 2018-P DDO WDDO-001 is the subtlest doubled die in the Shield Cent catalog and the single year with the highest Machine Doubling misidentification rate in the series. Careful examination is non-negotiable before claiming attribution.

2018-P DDO WDDO-001: genuine rounded thickening on the date and LIBERTY (genuine, left) vs. the extremely common flat Machine Doubling found on most 2018 cents (no value, right) — differentiation is the essential skill for this date

Pickup Points

1. Date “2018”: Extra thickness on all digits — must be rounded and raised, not flat or shelf-like.
2. LIBERTY: Thickened lettering visible under magnification.

Values

• MS65–66 Red:$10–$30

For the complete 2018 error guide, see 2018 Lincoln Cent Errors.

“Spitting Lincoln” Die Crack (2019–Present)

The “Spitting Lincoln” is the Shield Cent series’ most recognizable novelty error and a popular introduction to error coin collecting for beginners. A linear die crack extends from Lincoln’s mouth downward toward the rim or shoulder, creating the visual impression that the President is spitting. While not a cataloged die variety in the strict FS-number sense, its strong visual appeal drives consistent, predictable market demand.

“Spitting Lincoln” die crack: a raised, sharp linear crack extending downward from Lincoln’s mouth — distinguishable from a post-mint scratch by being raised above the coin surface rather than incuse

Diagnostics

• Location: Lincoln’s mouth area on the obverse, extending toward the rim or shoulder.
• Appearance: A RAISED, sharp, jagged linear crack — a true die crack. Post-mint scratches are INCUSE (cut into the surface), not raised. If the line is a groove rather than a ridge, it is damage.
• Value:$5–$20 depending on visibility and length of the crack.

For the complete 2019 error guide, see 2019 Lincoln Cent Errors.

Major Cuds & Die Chips — Shield Reverse Die Failures

Major Cud vs. Interior Die Chip: the cud (left) is a raised featureless blob connected to the rim ($20–$100+); the interior die chip (right) does not touch the rim — the rim connection is the key value distinction

The Shield reverse design — with its intricate vertical lines, central scroll, and “ONE CENT” inscription — creates numerous stress points on the die face, resulting in a higher-than-average incidence of die chipping and cud formation compared to the simpler Lincoln Memorial reverse.

• Major Cuds ($20–$100+): A catastrophic die break connected to the rim, producing a raised featureless blob that obliterates part of the field and design. The anomaly MUST touch the rim to qualify as a true cud. A “Retained Cud” — where the broken die piece is held in place but displaced — creates a shelf-like design displacement and is also collectible. Value is entirely size-dependent.
• Interior Die Chips ($1–$5): Smaller raised blobs of metal found most commonly on the edges of the central scroll labeled “ONE CENT” or obscuring letters in “E PLURIBUS UNUM.” They do not touch the rim. Generally nominal value.
• Grease-Filled Dies ($2–$10): Accumulated grease or debris in the die fills the incuse design details, preventing metal from flowing into those areas during striking. The result is obliterated or missing design elements — for example, missing letters in “LIBERTY” — with a smooth, mushy texture. Value depends on severity and completeness of the missing element.

Lincoln Shield Cent 2017 Varieties: Floating Head, Striking Errors & More

Beyond the 2017-P Doubled Ear FS-101 covered in the Trophy section, the 2017 Lincoln cent is notable for two additional phenomena: the widely collected “Floating Head” die polish variety and the historical milestone of the restored Philadelphia “P” mint mark. For Denver (D) 2017 cents, no major DDO varieties are documented — striking errors and die cracks are the primary targets. General striking errors (off-center strikes, broadstrikes) applicable to all Shield Cent years are also covered in this section.

2017 “Floating Head” Die Polish Variety

2017 “Floating Head” die polish variety: Lincoln’s neck is absent or nearly absent while all other design elements retain full sharpness — the shallowest design detail was abraded away by aggressive die polishing

The “Floating Head” is caused by the aggressive polishing of the die face to remove clash marks or erosion. The polishing process abrades the shallowest design elements first — in this case, the neck connecting Lincoln’s head to his shoulders. The result is a portrait in which the head appears to float above the shoulders with no connecting neck detail.

• Diagnostic: Lincoln’s neck is absent or nearly absent, yet LIBERTY, the date, and IN GOD WE TRUST all retain full, sharp detail. This distinguishes the genuine variety from circulation wear, which removes shallow details uniformly across the entire coin.
• Value:$3–$10. Classified as a polishing anomaly rather than a major die variety, but it has a dedicated following and consistent market demand among Shield Cent specialists.

Off-Center Strikes & Broadstrikes (All Years)

Off-Center Strike vs. Broadstrike on Lincoln Shield Cents: off-center strike shows a crescent of blank planchet with the design shifted to one side (left); broadstrike shows an expanded coin struck without the collar resulting in a wider, thinner coin with a plain edge (right)

Off-Center Strikes occur when the planchet is not properly centered over the lower die at the moment of striking, leaving a crescent of unstruck blank planchet metal.

• <10% off-center: Nominal value; generally considered a quality control variance rather than a collectible error.
• 10–50% off-center:$10–$30. Value is significantly higher when the date and mint mark remain fully visible within the struck portion.
• >50% off-center: Value may decrease if the date is lost to the unstruck area, though strong eye appeal can maintain premiums with experienced buyers.

Broadstrikes occur when the coin is struck without the retaining collar that forms the edge. The coin expands outward, appearing wider and thinner than a standard cent, with a plain, uneven edge lacking the normal bevel.

• Value:$10–$25. To command a full premium, the coin must be clearly larger in diameter than a standard Shield Cent and show fully struck design detail.

Lincoln Shield Cent Proof Values

Proof Lincoln Shield Cents are struck at the San Francisco Mint bearing an “S” mint mark, using specially prepared dies and planchets to produce mirrored fields and frosted devices. They are distributed annually in standard and silver proof sets.

Standard proof Shield Cents are collectible items but generally trade near or at issue price unless they exhibit a major documented error or achieve perfect PR70 Deep Cameo grades. The NGC Variety Plus database for Lincoln Shield Cents tracks any documented proof varieties and is the recommended starting point for researchers.

• Standard Proof (PR65–68 DCAM):$1–$10 — generally at or near issue price
• Perfect PR70 Deep Cameo: Commands a premium above standard grades
• Proof with Major Error: Proof cents struck off-center, on wrong planchets, or exhibiting a dramatic die variety can command substantial premiums. Submit to PCGS or NGC for attribution before selling any proof with an apparent error.

Grading Lincoln Shield Cent Error Coins

The Critical Role of Color Designation

The copper plating on Shield Cents means every Mint State example receives a color designation alongside its numeric grade: Red (RD), Red-Brown (RB), or Brown (BN). For die variety premiums, Red (RD) designation is essential — an MS65 RD example of the 2014 DDO FS-101 can be worth three to five times the same variety in MS65 BN. Store all uncirculated error candidates in inert, airtight holders immediately to prevent toning.

Error-Specific Grading Considerations

• Doubled Dies: The error itself does not penalize the numeric grade — a coin with strong doubling is graded on surface preservation, strike, luster, and eye appeal. However, die state matters: a coin from a worn late die state showing weaker doubling grades identically on preservation but commands less variety premium than an early die state specimen.
• Die Cracks and Cuds: These are mint-caused and do not reduce the assigned grade. They can actively enhance collector interest and premium.
• Plating Issues: Any zinc rot, split plating, or copper stripping results in a “Details” or “Genuine” grade designation (e.g., “MS65 Details — Environmental Damage”), which significantly reduces market value.

When to Submit for Professional Grading

Professional grading by PCGS or NGC is recommended for any variety expected to sell for $50 or more. The certification premium consistently more than offsets the grading fee for major trophy and findable varieties. The Lincoln Cents specifications reference is useful for verifying proper planchet weight and composition before submission.

Lincoln Shield Cent Error Authentication

Authentication for Lincoln Shield Cent errors concentrates on two central challenges: distinguishing genuine Class IX doubled dies from worthless Machine Doubling, and separating legitimate die-struck anomalies from environmental zinc-copper plating defects.

Weight Protocol

All Lincoln Shield Cents — regardless of year — should weigh 2.50 grams with a diameter of 19.05mm. Use a digital scale with 0.01g precision. A coin weighing significantly more than 2.50g may indicate an off-metal strike; significantly less may indicate a broadstrike (expanded diameter, thinner profile).

Plating Integrity Verification

Before attributing any raised anomaly as a die error, assess plating integrity under oblique lighting:

• Raised rounded dome with smooth luster over it → Plating Blister (no value)
• Dark, powdery, crumbling, or crater-like surface area → Zinc Rot (environmental damage)
• Solid, irregular raised fragment with sharp jagged boundaries → possible Die Chip (nominal value)
• Raised, rounded bulbous extra thickness with notched serifs → potential Doubled Die (significant value — submit for attribution)

Die Variety Attribution Standard

For doubled die claims, the coin must show ROUNDED thickening with NOTCHED serifs — not flat, shelf-like Machine Doubling. Third-party attribution by PCGS or NGC is mandatory for any variety expected to sell above $50. Both services reference NGC Variety Plus and PCGS CoinFacts for FS-numbered Shield Cent varieties.

Common Alterations to Avoid

“Science experiment” cents — coins stripped of copper plating with acid to mimic an unplated blank — show a dull, etched, or pitted surface and lack mint luster and radial flow lines. A genuine unplated cent would exhibit clean radial flow lines, bright zinc-gray luster, and weigh exactly 2.50 grams.

Where to Buy and Sell Lincoln Shield Cent Error Coins

Lincoln Shield Cent errors trade actively across several established platforms. For trophy-class varieties (2014 DDO FS-101, 2017 Doubled Ear, 2023 Extra V), certified PCGS or NGC examples consistently achieve the best realized prices.

• GreatCollections: A leading auction platform for certified modern error coins. The documented 2014 DDO FS-101 PCGS MS-67 sale at GreatCollections is a benchmark for trophy-tier pricing. GreatCollections specializes in certified coins and provides transparent price history.
• Heritage Auctions: The leading numismatic auction house for high-grade certified errors. The 2014 DDO FS-101 consistently realizes $250–$450 for MS66 Red examples through Heritage.
• PCGS CoinFacts: Use the PCGS CoinFacts auction price history to establish defensible market value before buying or selling any certified Shield Cent variety.
• Local Coin Dealers: For raw (uncertified) examples below the $50 certification threshold, local dealers offer immediate liquidity. Expect 20–40% below certified Mint State values for raw coins due to the grading cost the buyer will absorb.

Before selling any Shield Cent variety with an expected value above $50, professional authentication by PCGS or NGC is strongly recommended. The certification premium on trophy varieties routinely justifies the cost.

Lincoln Shield Cent Error FAQs

Methodology & Sources

Values in this guide represent typical certified (PCGS/NGC) auction and retail prices as of early 2025 for MS65–66 Red examples, drawn from documented realized prices at GreatCollections and Heritage Auctions. Raw, circulated examples of die varieties typically trade at 20–40% of certified Mint State values. yearRange.end: 2025 was applied based on the shield_modern era year_end of 2025 in the series calculator data, consistent with the latest year appearing in the subpage inventory.

Primary Sources

• Wexler’s Die Varieties — Single-Squeeze Hubbing — Technical foundation for Class IX doubling diagnostics and WDDO attribution codes
• CONECA — Single-Squeeze Hubbing history — Attribution system reference and hubbing chronology
• PCGS CoinFacts — 2014-P DDO FS-101 — Population data and auction price history for series flagship variety
• PCGS Auction Prices — 2017-P Lincoln Shield Cent — Source for $655 MS67+ Doubled Ear auction record
• GreatCollections — 2014 DDO FS-101 PCGS MS-67 — Trophy-tier auction benchmark
• NGC Variety Plus — Lincoln Shield Cents — Variety registry, attribution, and proof variety tracking
• Error-Ref.com — Plating Blisters — Definitive reference for plating defect identification
• Numismatic News — 2015-P Doubled Die — Original discovery report for WDDO-006
• Variety Vista — 2014-P DDO-001 — Diagnostic reference for FS-101 attribution
• Lincoln Cents — Composition & Specifications — Planchet weight, diameter, and metallurgical reference
• Wexler’s Die Varieties — 2010-P DDO listings — First-year Shield Cent variety catalog