Ministry of Education, 1994
Buku Teks
Gordon, Robert Aaron, author
Columbia University Press, 1959
Buku Teks
Lewis, Ralph G., author
St. Lucie Press, 1994
Buku Teks
McCorkle, Chester O., author
Jossey-Bass Publishers, 1982
Buku Teks
Committee on the Student in Higher Education
Hazen Foundation, 1968
Buku Teks