Descriptive Catalogue of the Postage Stamps and Post and Letter Cards of Siam 1883-1919 prepared for the Siam Philatelic Society by R.S. le May, W.J.F. Williamson and E. Wyon Smith (1920, rare and early book on Thailand philately!) and Postal Progress in Siam 1885-1925 by Siam's Ministry of Communication (1925, rare book including colour photo plates)
