Gifford, E. W.
University of California Press, 1956
Buku Teks
Alexander, John
Humanities Press, 1970
Buku Teks
Vats, Madho Sarup
Government of India Press, 1940
Buku Teks
Belshaw, Cyril S., author
Royal Institute of International Affairs, 1950
Buku Teks
Weyl, Walter E.
N.Y. Harper & Row , 1964
Buku Teks