Williams, Robert, author
Gower, 1991
Buku Teks
Ferdi Julias Chandra, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2012
UI - Skripsi (Membership)
OConnor, Karen, author
Addison Wesley Longman, 2001
Buku Teks
Sayre, Wallace S., author
Barnes & Noble, 1964
Buku Teks
Posey, Rollin Bennett, author
Littlefield, Adam, 1958
Buku Teks