Koch, Hans
The Unesco Press, 1975
Buku Teks
UNESCO, 1977
Buku Teks
Botombele, Bokonga Ekanga
The Unesco Press, 1976
Buku Teks
Mbughuni, L.A.
The UNESCO Press, 1974
Buku Teks
The Ministry of Foreign Affairs of the German Democratic Republic, 1961
Buku Teks