皮带轮必须加护罩 Pidailun bixu jiahu zhao Designer Sichuan Petroleum Administration Bureau of Drilling (四川石油管理总局钻探局) Date early 1950s Publisher First Printing Factory of the Northwest Military Region (西北軍區第一印刷廠) Size 78x54 cm. Call nr. BG E37/283 Collection Landsberger collection