Langley, Russell, author
Dover , 1971
Buku Teks
Fraser, D.A.S., author
John Wiley & Sons, 1967
Buku Teks
Tippett, L. H. C.
Williams and Norgate , 1952
Buku Teks
Yamane, Taro, author
New York University, 1967
Buku Teks
Croxton, Frederick E., author
Prentice-Hall, 1960
Buku Teks