This site by Jun Da contains a lot of very interesting resources for anyone who wants dig deeper into frequency lists. One set of data I haven't found anywhere else is a frequency list of syllables... Read more.

lingua.mtsu.edu

This is the best overview of spaced repetition research I have seen online or offline. It's thorough, well-argued and probably covers more than you were looking for. It's not specifically about Chi... Read more.

gwern.net

*The following introduction was written by John Renfroe and published here: [Learning Classical Chinese is for everyone (no, seriously!)](https://www.hackingchinese.com/learning-classical-chinese-... Read more.

amzn.to

ChineseMe is the most integrated Mandarin course, designed for motivated learners who have decided to become fluent. It is an interactive textbook that adapts itself to your interests. The course i... Read more.

chinese-me.com

Have you ever wondered what a small 二 or weird symbols that look like 〻 or 々 mean in Chinese handwriting? These aren't characters you normally find in printed books, but they do exist in handwritin... Read more.

en.wikipedia.org