20th Century Stamped Envelopes and Wrappers of the United States, by Prescott Holden Thorp.  An illustrated, priced specialized catalogue; the definitive work on its topic.  Please see scan of INDEX for contents.  Includes an appendix listing price revisions to all 19th Century entires as listed in the Thorp-Bartels, First Edition. 1968, hardcover, clean covers & spine, 205 unmarked pages, illustrated in B&W, like new but for former owners name on the frontispiece.  Size: 6" X 9".