19th CENTURY PRIVATE CITY POSTS
| A18.01 | Die Deutsche Privatpost, Vol. III by H. Meier zu Eissen, 1991, 494p. |
| A18.02 | Die Deutsche Privatpost, Vol. IV by H. Meier zu Eissen, 1997, 537p. |
| A18.03 | Handbuch der Deutschen Privatpostwertzeichen by C. Schmidt, Vol. I, Stamps, 1939. (A very authoritative treatment of the private posts). |
| A18.04 | Handbuch der Deutschen Privatpostwertzeichen by C. Schmidt, Vol. II, Stamps, 1939. (A very authoritative treatment of the private posts). |
| A18.05 | Die Marken der Hamburger Boten - Institute by J. Dieks |
19th CENTURY PRIVATE CITY POSTS Clippings
| A18.500CL | Betrachtungen zur Privatposten Mannheim, clipping, 6p. |
| A18.501CL | The German Privatposts II - Berlin / The German Privatposts III - Overprints by P. Greenlaw, clippings from Global Stamp News, Feb. / March 2004. |