Various brochures & newspaper article: Ott, C., the postmark the Hanseatic league cities (1925) and the postmark from Schleswig Holstein (1925) ; Berchelmann, Dr. W, the Thurn and Taxis small postal agency and the rural mail messenger system in the Grand Duchy Hessen (1925) ; Reinheimer, A., illustrated price catalog of the German postal devaluation types (1894), catalogue of the German devaluation types from 1849-1875, booklet and II., with 600 illustration (approximate. 1900), in addition to it fanfold with seeming 1000 illustration condition III-V.