Larousse, 1972
Buku Referensi
Wertheim, Jane
Usborne Publishing, 1986
Buku Referensi
Saunders, 2003
Buku Teks
Ida G. Dox [and others]
West Pub., 1997
Buku Referensi
editor in chief, Charles A. Ford
Encyclopedia Britannica Educational Corporation, 1969
Buku Referensi