Description: Mi.No. 575/577 UPU all with overprint of air mail, complete sheets. Stamp 3 din with errors of overprint on 1st field (broken VIO in AVIONSKA) 4th field (broken OŠ in POŠTA) 9th field (poorer printed Š in POŠTA). Stamp 5 din with error of print 1st field (white cheek). Good qualtiy, rare.