Robinson, Vester, author
Reston Publishing Company, 1974
Buku Referensi
Genn, Robert C., author
Parker Publishing Company, 1977
Buku Referensi
Lenk, John D., author
McGraw-Hill, 1995
Buku Referensi
Genn, Robert C., author
Parker Publishing Company, 1977
Buku Referensi
Namgostar, M.
Reston Publishing, 1977
Buku Teks