Serbia: 1917 (26 December). 8h Feldpost postal stationery card additionally franked with 10h Charles I portrait Austro-Hungarian Military Post stamp from a civilian in Serbia addressed to Sgt. Major of Serbian Engineers (Railways) in Salonica via neutral Switzerland tied by MLADENOVAC datestamp and highly unusual 15 August 1918 Serbian Field Post 999 arrival cds., red Austrian #113 and violet Serbian #21 censor cachets. Very scarce.
