Gunther, John, 1901-1970, author
Harper & Brothers, 1942
Buku Teks
Gunther, John, 1901-1970
Hamish Hamilton, 1939
Buku Referensi
Eleqant, Robert
Avon Books, 1991
Buku Teks
Compton, Charles, author
McGarw-Hill, 1979
Buku Teks
Downs, Anthony
Little, Brown and Co., 1967
Buku Teks