“Dowodztwo Szpitala Chirurgicznego W.P. w Wilnie Amer. Czerw.Krzyz - American Red Cross”, violett three line-cachet on post card with cds. “GŁÓWNA POCZTA POLOWA No. VII -3.6.1920” to Krakow, very fine, unique card confirming the ARC activity on the eastern front, signed Petriuk with certificate (2025)
