Browning, Carl H., author
Oxford University Press, 1937
Buku Referensi
Metcalf, Richard W., author
Harcourt Brace Jovanovich, 1990
Buku Teks
McGraw-Hill, 1981
Buku Teks
Sandige, Richard S., author
McGraw-Hill, 1978
Buku Teks
Little, Brown & Co., 1979
Buku Teks