Literature. Handbooks, etc. 'SFF:s Handbok Del I–III' in three separate soft bound volumes (Sveriges Filatelist-Förbund, 1962–1964), 'Tidiga svenska datumstämplar del I' (SFF) and Aktuellt om Posthistoria, Nr 3 (1991), 8 (2003) and 12 (2014). All are used. (7).
