Todaro, Michael P., author
Longman, 1989
Buku Teks
Todaro, Michael P., author
Longman, 1992
Buku Teks
Fryer, D.W., author
McGraw-Hill, 1965
Buku Teks
edited by P. Ebow Bondzi-Simpson
Praeger, 1992
Buku Teks
Kahn, Herman
Morrow Quill Paperback, 1979
Buku Teks