Burkill, J.C.
Cambridge University Press, 1962
Buku Teks
Polya, George, author
Stanford University Press, 1962
Buku Teks
Das, G.
McGraw-Hil Publishing , 1993
Buku Teks
Beals, Richard
Springer-Verlag, 1980
Buku Teks
Bruckner, Andrew M
Ptrentice-Hall International, INC, 1997
Buku Teks