Our Discord: https://discord.gg/ajezQHdnRU. Please email mathteca@gmail.com if any organization or society wants to partner with Mathteca.
JPhO (in Japanese)
Moscow City Physics Olympiad (In Russian)
MIPT (Fiztekh) Physics Olympiad (In Russian)
Saint Petersburg Physics Olympiad (In Russian)
Belarusian Physics Olympiad (In Russian)
EstPhO (in Estonian)
Eötvös Competition (in Hungarian)
Hong Kong Physics Olympiad Lecture Notes (2016): http://hkpho.phys.ust.hk/Protected/pastnotes_2016.html
HKBU Phrase 1 Lecture (2016-2017): http://hkpho.phys.ust.hk/Protected/HKBUnotes_2016.html
Chinese Physical Society: http://www.cps-net.org.cn/
Physical Society of Hong Kong: https://www.pshk.org.hk/
Sing Yin Physics Olympiad Solution: https://www.youtube.com/watch?v=_4A5NIyy1y4&list=PLHf8BF_xelpArBTNY1xev0LTXz6C35YuZ