Early Yugoslavia - Croatia-Slavonia 1918 Issues

I found these in a packet. They are supposedly 1918 Croatia-Slavonia (overprinted Hungary). All for mint with full gum.

The Scott catalog states additional printings were done "surreptitiously" which I interpret to mean they were the same as those sold but were not sold by post office.

Is there any more information on these?

Here is SG's note in SG Part 3 Balkans in their Yugoslavia listing:

II. ISSUES FOR CROATIA

100 Filir (Heller) = 1 Kruna (Krone)

The provisional issues on Hungarian stamps were sold in Yugoslavian "heller" and "krone" currency, but as this is not expressed on the stamps (except for Nos. 69/73) we have retained the Hungarian descriptions to facilitate reference to the original stamps.

Nos. 53/D92 are the stamps officially overprinted and placed on sale at post offices. Because of a shortage of some denominations, permission was given for the printers to accept unoverprinted Hungarian stamps in private possession and either exchange them for overprinted stamps of an equivalent value, from which come many errors, test printings etc., or to overprint them for later collection. Thus many stamps not listed exist overprinted from the original plates, and those that are listed also exist with the "wrong" overprint.

The original overprinting plates had been destroyed by mid-February 1919 but because of continuing demand, mainly from collectors and dealers, new plates were made and the printers continued to overprint any Hungarian stamps presented to them. Forgeries also exist.

Overprints signify "Croatia, Serbs, Croats, Slovenes".

Mine are likely the philatelic demand related printings.

More info

https://worldstampsproject.org/stat...mps-croatia/