Pirages, Dennis C.
Duxbury Press, 1978
Buku Teks
Watson, Adam, author
Routledge , 1997
Buku Teks
Fernandez, Alejandro M., author
NSDB-UP Integrated Research Program, 1977
Buku Teks
International forums of Sao Paulo and Geneva , 1956
Buku Teks
James, Preston E., author
John Wiley & Sons, 1980
Buku Teks