Blij, Harm J.. de
John Wiley & Sons, 19880
Buku Teks SO
Knapp, B.J.
George Allen and Unwin, 1982
Buku Teks SO
Hidore, John J.
Scott, Foresman, 1974
Buku Teks SO
edited by Otis W. Freeman and John W. Morris
McGraw-Hill, 1958
Buku Teks SO
Heintzelman, Oliver H.
Prentice-Hall, 1960
Buku Teks SO