Graefe, Heinz
Munchen Carl Gerber 1962
Buku Teks
Backmann, Kurt
Berlin : Tag der Promotion, 1939
Buku Referensi
Palmen, Connie
Promotheus, 1998
Buku Teks
Teryaev, G.
Foreign Languages Publishing House, 1954
Buku Teks
Schleicher, August
Amsterdam John Benjamins B.V. 1983
Buku Teks