Grindstaff, Carl F., author
Christopher Publishing House, 1981
Buku Teks
edited by Stanley Johnson
John Wiley & Sons, 1973
Buku Teks
edited by William Petersen
Macmillan, 1972
Buku Teks
Thompson, Warren S., author
McGraw-Hill, 1970
Buku Teks
Artikel Jurnal