An Infinitely Large Napkin [pdf]
Evan Chen is a very valuable person in the Math Olympiad scene.<p>The Geometry book [1] he wrote in high school is required reading for any serious competitor and I believe he is the main responsible for some bringing some techniques into the olympic meta, such as Barycentric Coordinates.<p>Also, his blog post [2] about writing is one of the best ones I've ever read.<p>[1] <a href="https://web.evanchen.cc/geombook.html" rel="nofollow">https://web.evanchen.cc/geombook.html</a>
[2] <a href="https://blog.evanchen.cc/2015/03/14/writing/" rel="nofollow">https://blog.evanchen.cc/2015/03/14/writing/</a>