Harris, J. Manville.
Barron's Educational Series, 1992
Buku Teks SO
Kolde, Endel J.
Prentice-Hall, 1968
Buku Teks SO
Weston, J. Fred [John Fred], 1916-
Richard D. Irwin, 1972
Buku Teks
Ward, Richard
Prentice-Hall, 1965
Buku Teks SO
edited by R.N. Cooper
Penguin Books, 1969
Buku Teks SO