The stamps were overprinted in 'Jović Printing Works' in Banja Luka on 18.04 or 19.04.1941 and delivered to the post office. They remained on sale until 23.04.1941 by which time the entire stock of 1000 stamps of each value was sold. Formally, the Banja Luka provisional issue was valid until 30.04.1943 and on the entire territory of the Independent State of Croatia. All known postal items, except the one, were sent from Banja Luka...
1941 Banja Luka provisional issue, express registered letter, franked with 22.50 kn and 1 din, sent from Zagreb (24.IV.43) to Banja Luka (25.IV.43). The only known express delivery letter and the only letter using the issue posted outside Banja Luka. Certificate Ercegović, Vilfan, Marinšek.
