Approved as a teaching aid by the Ministry of National Education of the German Democratic Republic. Developed by the academy of pedagogical sciences of the GDR institute for teaching aids. Rights Society: AWA Matrix / Runout: 8 75 138 + 1B A87 E C (Runout Side A) Matrix / Runout: 8 75 138 + 2A A87 C (Runout Side B) Other: Ag 511/01/86/A (Printing date code)