McGuire, Joseph W.
McGraw-Hill, 1963
Buku Teks SO
Thomas, Rollin G.
Prentice-Hall, 1959
Buku Teks SO
Alexander Hamilton Institute
Alexander Hamilton Institute, 1971
Buku Referensi
Ramo, Simon
McGraw-Hill, 1983
Buku Teks SO
Tinker, Anthea
Longman , 1984
Buku Teks