Cochran, Thomas C.
McGraw-Hill, 1972
Buku Teks SO
Pole, J.R.
University of California Press, 1993
Buku Teks
Bailey, Thomas Andrew, 1902-1983
D.C. Healt, 1987
Buku Teks
Herget, James E.
Texas: Rice University Press, 1990,
Buku Referensi
Ferrell, Robert H.
W.W. Norton, 1959
Buku Teks