Sinco, Vicente G.
University of Philippines , 1959
Buku Teks
Lachica, Eduardo
Solidaridad Publishing House, 1971
Buku Teks
Davis, William G.
University of California Press, 1973
Buku Teks
Timberman, David G., author
M.E. Sharpe, 1991
Buku Teks
editors, Marlon A. Wui, MA. Glenda S. Lopez
Third World Studies Center, 1997
Buku Teks