Martin, Michael Rheta, author
The Bobbs Merrill, 1968
Buku Referensi
Wilgus, A. Curtis, author
Barner & Noble, 1963
Buku Teks
edited by Howard J. Wiarda, Harvey F. Kline
Westview Press, 2007
Buku Teks
Susana Nuccetelli, Ofelia Schutte, Otavio Bueno
Wiley, 2013
Buku Teks
Crawford, William R., author
Frederick A. Praeger, 1961
Buku Teks