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American Mathematics Competitions - http://www.unl.edu/amc/
Organization that administers the AMC, the AIME, and the USAMO, with information about the contests, math problem archives, recommended reading lists, and other resources for students interested in mathematics. |
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Crux Mathematicorum with Mathematical Mayhem - http://journals.cms.math.ca/CRUX/
Problem-solving journal at the senior secondary and university undergraduate levels. |
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Australian Mathematics Trust - http://www.amt.canberra.edu.au/
Sponsors a number of competitions in the Australian continent. |
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Valentin Vornicu's MathLinks - http://www.mathlinks.ro
Math Olympiad Problem Solving site with a weekly contest, resembling IMO in difficulty, with a large math forum and downloadable materials. |
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Mathematics Archives - http://archives.math.utk.edu/contests
links to contests, problem sets, journals sites. |