Update

I made the following changes in Tank strength and losses – Eastern Front: Added ‘Waffen und Geheimwaffen des deutschen Heeres 1933 – 1945’ as a source and corrected the total numbers of German vehicles (my original numbers were slightly lower than they should be because I didn’t add special tanks like command, recovery and flak vehicles).

I added the following in SOE codes and Referat Vauck, paragraph ‘Key taken from a poem’:

Note that Marks doesn’t say anything about six consecutive letters. On the contrary in his book page 324 he says ‘every poem code message began with a five letter indicator group to show which five words of the poem had been used’.