Schnitzer, Martin C.
Rand McNally College Publishing , 1978
Buku Teks
Martin Basiang
Red & White Publishing, 2009
Buku Referensi
Boone, Louis E.
Dryden Press, 1996
Buku Teks
Boone, Louis E.
Dryden Press, 1990
Buku Teks
Allen, Robert E.
Addison-Wesley, 1983
Buku Teks SO