Ginsberg, Gerald L.
John Wiley & Sons, 1981
Buku Teks
Charles A. Harper, editor-in-chief
McGraw-Hill, 1977
Buku Referensi
Jones, Thomas H.
Reston Publishing Company, 1978
Buku Referensi
Genn, Robert C.
Parker Publishing Company, 1981
Buku Referensi
Lenk, John D.
Prentice-Hall, 1982
Buku Referensi