The stamps are organized by design and denomination for the definitive stamps of this era.
Reference Books
2445-48 - 1990 25c Classic Films - Mystic Stamp Company
Book Or PDF Introduction Into US Classic Stamps (Heads) - Stamp Community Forum
Philatelic & Stamp-Collecting Hobby News Articles
Used Book in Good Condition
Micarelli Identification Guide to US Stamps: Regular Issues, 1847-1934
Daniel F. Kelleher Auctions, LLC Sale - 2003 Page 10
Scott The Micarelli Identification Guide To U.S. Stamps Regular Issues 1847-1934
iHobb.com Oceanside CA
U.S Postage Stamps, Essays & Proofs
By Charles N. Micarelli, Scott Publishing Co., 1991.
The Micarelli Identification Guide To U.S. Stamps 1847-1934 Scott 1991