Heling, Bureau Menno, author
Het Spectrum, 1994
Buku Referensi
Speiser, Werner, author
Safari-Verlag, 1946
Buku Teks
Fokkema, K., author
J.B. Wolters, 1939
Buku Teks
Seckel, Dietrch
W Kohlhammer , Stuttgart W Kohlhammer 1957
Buku Teks
Sarre, Friedrich, author
Berlin Bruno Cassirer 1923
Buku Teks