by Johannes Hochtl ...[and others]
Verlag Enzyklopadie Leipzig, 1960
Buku Referensi
Gotz, Dieter, author
Langenscheidt, 1993
Buku Referensi
edited by Rudolf Walther with the cooperation of Martin Strauss
Pergamon Press, 1976
Buku Referensi
de Vries, Louis, author
McGraw-Hill, 1959
Buku Referensi
Routledge, 1997
Buku Referensi