Orthogonal polynomial

https://www.encyclopediaofmath.org/index.php/Classical_orthogonal_polynomials  

https://www.encyclopediaofmath.org/index.php/Orthogonal_polynomials  

https://en.wikipedia.org/wiki/Orthogonal_polynomials

https://arxiv.org/pdf/1712.03155.pdf

http://fdslive.oup.com/www.oup.com/academic/pdf/13/9780198506720.pdf

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=BA513EAFA987B3C7F36B658EBE3907E4?doi=10.1.1.760.2995&rep=rep1&type=pdf

http://www.math.miami.edu/~morsej/Articles/flj.pdf

http://galton.uchicago.edu/~lalley/Courses/386/OrthogonalPolynomials.pdf

http://arxiv-export-lb.library.cornell.edu/abs/1701.02709  

http://arxiv-export-lb.library.cornell.edu/abs/1801.09099  

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.237.7629&rep=rep1&type=pdf 

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.757.619&rep=rep1&type=pdf

Igor Kortchemski

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/geometrie/gimo.pdf

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/mc97-98-01feb.pdf  

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/IMO/imo (1990 - 2002) Hojoo Lee.pdf

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/arithmetique/pen2005.pdf 

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/inegalites/i2006.pdf  

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/inegalites/psine2.pdf  

http://igor-kortchemski.perso.math.cnrs.fr/olympiades/Problemes/inegalites/psine1.pdf

Notices of American Mathematical Society

https://goo.gl/XVvXTz

Or generally (just replace the 201603 with yyyymm):

http://www.ams.org/journals/notices/201603/201603-full-issue.pdf

Or this URL as well:

http://www.ams.org/notices/201502/201502-full-issue.pdf

Polish Mathematical Olympiad 2016/17 - Mathematics Meta Stack Exchange

https://math.meta.stackexchange.com/questions/25020/polish-mathematical-olympiad-2016-17?rq=1

SIAM: Math Matters, Apply It!

https://www.siam.org/careers/matters.php

Try these problems from historical Tripos

A trip into Mathematical Tripos through its history

Looking at this:

http://maths-obsession.blogspot.sg/2015/05/searching-for-mathematical-tripos.html

Many links are outdated, so perhaps here are some updated links:

https://www.maths.cam.ac.uk/undergrad/pastpapers

And these are the pre-1878 era:

https://www.ocf.berkeley.edu/~lekheng/tripos/math-tripos-pre1878.pdf

And lots of others:

https://www.ocf.berkeley.edu/~lekheng/tripos/

https://tartarus.org/gareth/maths/tripos/

https://www.maths.cam.ac.uk/past-examination-papers

https://www.maths.cam.ac.uk/undergradnst/pastpapers