Grubel, Herbert G., author
Lexington Books, 1973
Buku Teks
Unesco , 1986
Buku Teks
Agrawal, Mahesh Chandra, author
[, Springer], 2012
eBooks
edited by Raphael Israeli
Curzon Press, 1989
Buku Teks
Sharif As-Saber
Rajiv Beri for Macmillan, 2009
Buku Teks