Crippen, G. M.
Research Studies Press, 1981
Buku Teks
Juaristi, Eusebio, author
John Wiley & Sons, 1991
Buku Teks
MIR, 1982
Buku Teks
Court, Nathan Altshiller, author
Barnes and Noble, 1952
Buku Teks
Schaaf, William L., author
Doubleday, 1962
Buku Teks