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Math Olympiads - http://cage.rug.ac.be/~hvernaev/olympiad.html
Collection of problem sets from International and National Mathematics Olympiads. |
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Tournament of Towns at Toronto - http://www.math.toronto.edu/oz/turgor/archives.php
Contest problems and solutions for The International Mathematics Tournament of the Towns. |
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Problem Page - http://www.math.wisc.edu/~talent/problems.html
Archive of problem sets and solutions from Wisconsin Mathematics, Engineering and Science Talent Search. |
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Madras College Mathematics Department Resources - http://www.madras.fife.sch.uk/maths/resources.html
Problems from UK Math Olympiads and a collection of training materials. |
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USSR Math Olympiad, 1961-1986 - http://members.tripod.com/~PertselV/RusMath.html
Problems without solutions. |