Genn, Robert C.
Parker Publishing Company, 1977
Buku Referensi
Lenk, John D.
McGraw-Hill, 1995
Buku Referensi
Genn, Robert C.
Parker Publishing Company, 1977
Buku Referensi
Namgostar, M.
Reston Publishing, 1977
Buku Teks
Lenk, John D.
McGraw-Hill, 1999
Buku Referensi