United States Postage Stamps, 1902-1935 by Max G. Johl (1976, Hardcover)

Max G. Johl’s work was originally published in the 1930s by Quarterman as a 4 volume set entitled The United States Postage Stamps of the Twentieth Century. It is a seminal work of philatelic scholarship. His work was updated and published in 1947 by H. L. Lindquist in a 2 volume set entitled The United States Commemorative Stamps of the 20th Century 1902-1947 to coincide with the 100th anniversary of the issuance of the first United States postage stamp. The updated 1947 editions are of better quality and include many more photographs and illustrations, but they cover only the commemorative issues of the period. This volume: The United States Postage Stamps, 1902-1935, is the Quarterman Publications 1976 update to Johl’s 1930 treatment of the regular, parcel post, and airmail issues.
Most philatelists consider these books essential for developing an understanding the United States stamps of the era. Johl describes the elements of every stamp in detail: from the commissioning of the stamp, to the design of the vignette, all the way through the production process. He also illustrates the errors and design flaws discovered after the stamps were issued. You will find data on the printing process, paper, watermarks, quantities issued, perforations, plate numbers, earliest known use (EFO), and the postal cancellations used while the stamp was in service.
All of these works are now out of print and hard to find. I’ve seen the 1930 and 1947 editions selling for as much as $75 per volume. I highly recommend that you purchase a set if you find them at a price you can afford.