The rarest postage stamp among Slovenian provisional issues is a stamp with an overprint on Hindenburg 4pf. Only 20 sheets were overprinted. It appears on the market almost exclusively as a single piece. I only know two blocks of four and one block of six, which is also the largest known multiple...
1945 Maribor provisional issue, Mi. No. I, block of six with upper margin, position 3-5/13-15. The largest known multiple. Certificate Marinšek.
