Ross, John A., author
Columbia University, 1989
Buku Teks
Zaidan, George C., author
The John Hopkins University Press, 1971
Buku Teks
edited, Bernard Berelson
University of Chicago, [date of publication not identified]
Buku Teks
JHPIEGO, 1993
Buku Teks
edited by Maria Wawer ... [and others]
Westview Press, 1985
Buku Teks