Some geometry problems ( like this and this ) have short solutions if we use involutions. What references are there for solving geometry problems using involutions? I am particularly interested in theoretical aspects of involutions, and maybe a reference with solved problems like these two presented in the links.

There are quite a few problems on AoPS that are solved using involutions. I searched there for help, but it seems that the user that posted most of the solutions (grobber) is not active anymore. There was a suggestion to make a teaching article for such problems but there was no one to finish the task. This question was on StackExchange for almost a month now without any answers or comments, that's why I've posted it here.