Modern Reference Bomar's 1986 "Postal Markings of United States Expositions". 206 pages of Postal Markings from all the US expositions from 1853 to 1984 with a cataloging system, descriptions and pictures of the postmarks, covers and more. William J. Bomar was the leading authority on US Postmarks. An important reference book. Size: 7 1/4" wide by 10 1/4" high. Condition: Excellent.