Levy, Haim, author
Prentice-Hall, 1878
Buku Teks
editor, Gary Fromm
The Brookings Institution , 1971
Buku Referensi
Dube, Yves, author
Queen's Printer, 1957
Buku Teks
Murdick, Robert G., author
McGraw-Hill, 1968
Buku Teks
Wilkes, F. M.
John Wiley & Sons, 1977
Buku Teks