Bohannan, Paul, author
The National History Press, 1964
Buku Teks
Mazrui, Ali Al Amin
Little, Brown & Co., 1986
Buku Teks
Murdock, George Peter, author
McGraw-Hill, 1959
Buku Teks
Murdock, George Peter, author
McGraw-Hill, 1959
Buku Teks
Nielsen, Waldemar A., author
Atheneum, 1966
Buku Teks