PHTST
Problems and How to Solve Them
Produced by the Centre for Education in Mathematics and Computing.
Faculty of Mathematics
University of Waterloo
Waterloo, Ontario, Canada
P. Zeitz
The Art and Craft of Problem Solving
STEP
Sixth Term Examination Paper
Published annually by Cambridge University
APCM
Advanced Problems in Core Mathematics
S.T.C.Siklos
Available online at http://www.admissionstestingservice.org/images/121909-advanced-problems-in-mathematics-.pdf
Needham VCA
Visual Complex Analysis
by Tristan Needham
Clarendon Press, Oxford, 1997