In 1959, the development of the 30 mm self-propelled anti-aircraft complex (codename PROGRES) was included in the plan for the technical development of military equipment.
Source : ŠTAIGL, Jan Weapons production in Slovakia in 1954 - 1960, p. 68, MILITARY HISTORY 2003/1 VHÚ Bratislava
Source : ŠTAIGL, Jan Weapons production in Slovakia in 1954 - 1960, p. 68, MILITARY HISTORY 2003/1 VHÚ Bratislava