edited by Andrea Axelrod, Jude Dratt and Stuart Sucherman
Ford Foundation, [Date of publication not identified]
Buku Teks
University of Southern California, 2014
Buku Referensi
Lonely Planet Publication, 2003
Buku Teks
Bowman, Arthur G.
Prentice-Hall, 1970
Buku Teks
Kamm, Ernest R
Macmillan, 1981
Buku Teks