Articles of General Interest
The Art of Printing Line-Engraved Stamps
Quantity Issued Estimates for Classic U.S.
Guide to the Grills on U.S. Stamps
U.S. Bank Note Stamp Paper Types
The Secret Marks of the U.S. Banknote Issues
Watermarks on U.S. Postage Stamps
Flat Plate Vs Rotary Press Vs Offset
Private Perforations
Gum Breakers on U.S. Stamps
Wet Vs Dry Printing Methods

1908-1922 Series - Washington Franklins
Franklins: Scott 331//547
Washingtons: Scott 332//546
The Washington Franklin Identifier
Chart of All 1¢ Franklins
Chart of All Two Cents in Letters Washingtons
Chart of All 1¢ Washingtons
Chart of All 2¢ in Numerals Washingtons
Chart of All 3¢ Washingtons
Chart of All 4¢ Washingtons
Chart of All 5¢ Cent Washingtons
Types I, Ia, II and III - Flat Plate 2¢
Types IV, V, Va, VI and VII of the Offset 2¢
Types I & II of the Flat Plate 3¢
Types III & IV of the Offset 3¢

1922-1935 Series
Scott 551 // Scott 723
Scott 599 Vs 599A and 634 Vs 634A

1933-1935 Farleys
Farley's Follies Identifier
Position Pieces on the Farleys

1938 Series - The Prexies
Scott 803-834 and 839-851
Prexie Coils of 1939

1954 to Present
Liberty Series - Scott 1030 to Scott 1059A
Prominent Americans - Scott 1278//Scott 1402
Americana Series - Scott 1581//Scott 1816
Great Americans - Scott 1844//Scott 2943
Transportation Coils - Scott 1897//Scott 2468
Perforations on Modern Issues

Newspapers & Periodicals
1865 - Scott PR1-PR8
1875-1894 - Scott PR9-PR101
1895 - Scott PR102-PR125

Departmental and Official Stamps
1873 & 1879 Agriculture - Scott O1-O9 & O94-95
1873 Executive - Scott O10-O14
1873 & 1879 Interior - Scott O15-O24 & O96-O103
1873 & 1879 Justice - Scott O25-O34 & O106-O107
1873 Navy - Scott O35-O45
1873 & 1879 Post Office - Scott O47-O56 & O108
1873 State - Scott O57-O71
1873 & 1879 Treasury - Scott O72-82 & O109-13
1873 & 1879 War - Scott O83-93 & O114-120

Postage Due Stamps
1879 Design - American - Scott J1-J28
1894 Design - BEP - Scott J29-J68
1930 Design - Scott J69-J86
1959 Design - Scott J87-J101

Special Delivery & Parcel Post Stamps
Special Delivery - Scott E1-E23
Parcel Post - Scott Q1-Q12 & JQ1-JQ5

Air Mail Stamps
Air Mail 1918-1944 - Scott C1-C31
Air Mail 1946-1969 - Scott C32-C76

Special Handling Stamps
Special Handling - Scott QE1-QE4