Levi, Werner
University of Minnesota Press, 1954
Buku Teks
Jaisingh, Hari, author
Siddharth Publications, 2005
Buku Teks
Kothari, Rajni, author
Little, Brown, 1970
Buku Teks
Levi, Werner
The University of Minnesota Press, 1953
Buku Teks
Brecher, Michael
Frederick A. Praeger, 1966
Buku Teks