The Third Reich issued this series of definitives depicting Adolf Hitler beginning 1 August 1941. The 42 Pf value was issued much later, in 1944.
Due to their design, these issues are commonly referred to as “Hitler Head” issues.
MiNr. 781-786 are typography on chalky paper, while MiNr. 787 onward are engraved on ordinary paper.
The stamps are similar to the later 20 March 1942/1944 and December 1942 Hitler definitives.
For booklets and sheets of these issues, see here and here.