Recommended and introduced by Trevor [here](http://www.hackingchinese.com/extensive-listening-challenge-october-2014-wrapping-up/#comment-646686). Each book (one for each level of the new HSK ex... Read more.

amazon.com

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

This website offers a large number of previous HSK and YCT Chinese proficiency tests, sorted by year and level. This is excellent for test preparation and/or benchmarking. Read more.

chinesetest.cn

Foreigncy provides daily digital flashcards, with audio, that prepare a user to read a foreign policy or economics from a regional source. The site also provide users with an English language summa... Read more.

foreigncy.org

This is a site where you can find theses and dissertations published in Taiwan. It's an excellent source if you want to find research about specific topics and improve your reading ability at the s... Read more.

ndltd.ncl.edu.tw

This website provides a large-scale psycholinguistic norm of 3,314 Traditional Chinese characters along with their naming latencies collected from 140 Chinese speakers. Several variables are gi... Read more.

ball.ling.sinica.edu.tw

This is a research paper detailing a study of the mutual intelligibility of Chinese topolects. Dialects were sorted into groups and then it was experimentally tested how much of words and sentences... Read more.

openaccess.leidenuniv.nl

This is a review of Perry Link's book about Chinese. This passage sums it up pretty well, and although I haven't read the book (yet), it's high on my list of books to get my hands on: "In writin... Read more.

lareviewofbooks.org