Here are some olympiad handouts I have prepared over the years; please email me if you find any typos or mistakes. Please feel free to contact me if you'd like hints for any of the problems or access to other handouts I have written (in English or Romanian).
Concyclicities in Tucker-like configurations (with Stefan Dominte), published in Mathematical Reflections, Vol 1, 2016.
Quadratic Congruences in Olympiad Problems (with Paul Stoienescu), published in Crux Mathematicorum, Vol. 43(8), 2017.