Walton, John
Johns Hopkins Press , 1959
Buku Teks
Hoy, Wayne K., author
McGraw-Hill, 2013
Buku Teks
Schargel, Franklin P., author
Eye on Education, 1994
Buku Referensi
Morphet, Edgar L. (Edgar Leroy), 1895- , author
Prentice-Hall, 1982
Buku Teks
Snowden, Petre E.
McGraw-Hill , 1998
Buku Teks