Wessely, J.E., author
Chicago dsb. Pollett Publ. 1946
Buku Referensi
Klatt, Edmund
Berlin Langenscheidt KG. Verlag buchhandlung 1961
Buku Referensi
Wichman, K., author
New York, David Mckay Company
Buku Referensi
Muller, F.
Groningen J.B. Wolters 1939
Buku Referensi
Muller J.Z.N., F.
Groningen J.B. Walters 1919
Buku Referensi