Woolley, Tyler A.
Burgess, 1969
Buku Teks
Ruppert, Edward E.
Saunders College, 1994
Buku Teks
edited by D.T. Anderson
Melbourne, 1998
Buku Teks
Wilmoth, James H.
Prentice-Hall, 1967
Buku Teks
Buchsbaum, Ralph
Chicago The University of Chicago Press, [date of publication not identified],
Buku Teks