35c, B1: The Intergovernmental Authority on Drought and Desertification is the theme of this set, which also shows flags and map of E. African member countries. In 1995 this group held a summit in Addis Ababa.
M50, M250: The Lichtenstein's Hartebeest is featured on this lovely WWF issue from 1993; once a far-ranging species, this ungulate now has a reduced range due to poaching, warfare and a recent Rindepest epidemic.
D1500: this issue celebrates cooperation with Taiwan, showing the flags of the two countries intertwined. Sao Tome is one of the few African countries that maintains relations with the Republic of China