Lenk, John D., author
Prentice-Hall, 1971
Buku Referensi
Lenk, John D., author
McGraw-Hill, 1995
Buku Referensi
Lenk, John D., author
Prentice-Hall, 1983
Buku Referensi
Hubert, Charles I. (Charles Irving), author
McGraw-Hill, 1969
Buku Teks
Grolle, Carl G., author
Parker Publishing Company, 1977
Buku Referensi