Kent, Sherman
Appleton Century Croffs, 1941
Buku Teks
Adams, Katherine H., author
Mayfield Publishing Company, 2000
Buku Teks
Dian Masniari, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2013
UI - Skripsi Membership
Gunner, Jeanne
Harper & Row, 1986
Buku Teks
Chandos, 2013
eBooks