Clarke, T., A Catalog Of Philadelphia Postmarks, 18th Century To T ...Clarke, T., A Catalog Of Philadelphia Postmarks, 18th Century To The Present, Part 1, Domestic Origin Markings, manuscript, handstamp, and machine, 1989, ca. 100 S., Part II, Additional Markings incl. B O B origin cancels (ship, foreign, air mail and railroads), received and transit backstamps, and registry postmarks, 1990, ca. 100 S., Part III, Back of the Book Origin Cancels, cont'd, and Auxiliary Markings, incl. Free, Paid, Locals, Meters,