Editing Basel problem (section)

==External links==
* [https://plus.maths.org/content/infinite-series-surprises An infinite series of surprises] by C. J. Sangwin
* [https://fylux.github.io/2017/03/30/Pi/ From ''ζ''(2) to Π. The Proof.] step-by-step proof
* {{citation |url= http://eulerarchive.maa.org//docs/translations/E352.pdf |title= Remarques sur un beau rapport entre les series des puissances tant directes que reciproques}}, English translation with notes of Euler's paper by Lucas Willis and Thomas J. Osler
* {{citation |url= http://eulerarchive.maa.org/hedi/HEDI-2003-12.pdf |title= How Euler did it |author= Ed Sandifer}}
* {{citation |url= http://www.personal.psu.edu/jxs23/p25.pdf |title= Beyond Mere Convergence |author= James A. Sellers |date= February 5, 2002 |access-date= 2004-02-27}}
* Robin Chapman, [http://empslocal.ex.ac.uk/people/staff/rjchapma/etc/zeta2.pdf ''Evaluating'' {{math|''ζ''(2)}}] (fourteen proofs)
* [https://web.archive.org/web/20181130113058/https://giphy.com/gifs/math-visualization-algorithm-xThuW9Pyh8jXvfbrUc Visualization of Euler's factorization of the sine function]
* {{citation |url= http://www.math.chalmers.se/~wastlund/Cosmic.pdf |title= Summing inverse squares by Euclidean geometry |author= Johan W Ästlund |date= December 8, 2010}}
** {{YouTube|d-o3eB9sfls|Why is pi here? And why is it squared? A geometric answer to the Basel problem}} (animated proof based on the above)

[[Category:Articles containing proofs]]
[[Category:Mathematical problems]]
[[Category:Number theory]]
[[Category:Pi algorithms]]
[[Category:Squares in number theory]]
[[Category:Zeta and L-functions]]