Luftpost 1793 Brosch. 1322 

Conn, E~l1Gt L:.: TLerr Pre~c~: Cor..I1i38ar~' l~irrnail 
of 1793. -0.0. 1911. 0.)9-49.8 [hOp.tt.J 
Aus: Posta1 History Journal. 1971, t:ay.