WB. Saunders, 1965
Buku Teks
Penalver, Rafael A., author
Arco Publishing, Inc., 1981
Buku Teks
Penalver, Rafael A., author
Arco Publishing, 1984
Buku Teks
edited by Philip E. Sartwell
Meredith Publ., 1965
Buku Teks
editors, John M. Last, Robert B. Wallace ; associate editors, Elizabeth Barrett-Connor [and others]
Appleton & Lange, 1992
Buku Referensi