Stansfield, William D., 1930-
Theory and problems of genetics
McGraw-Hill, 1982
Buku Teks
Kazmier, Leonard J.
Theory and problems of business statistics
McGraw-Hill, 2004
Buku Teks
Kelsen, Hans
Introduction to the problems of legal theory
Clarendon Press Oxford, 1992
Buku Teks
Dixon, John D.
Problems in group theory
Blaisdell, 1967
Buku Teks
Spiegel, Murray R.
Theory and problems of statistics
McGraw-Hill, 1961
Buku Teks