Vera Tomanic's postal certificate formerly belonging to a friend

This postal certificate for a package sent to the Zlatar Loborgrad camp near Zagreb, Croatia was issued in 1942. My sister Lilie sent the package with food to her friend Mira Rot, who was taken from Nova Gradiska to the Zlatar camp in 1941. I only know that Mira Rot was a Jew born in 1923 in Nova Gradiska. She was captured, not because she was Jewish, but because she was an active communist. Unfortunately she did not survive the war.