Official Touhou Fanbook released on April 27 of 2012. Containing information on every single character from Mountain of Faith to Ten Desires. If you recall, we had a similar book for EoSD to PoFV. Extending onto the characters the book contains 184 pages that has content regarding the religions in Gensokyo along with interviews with ZUN. The release date for the book was repeatably pushed back until finally being released.
Scans have been posted and you can read parts of the book on Touhou wiki if you desired. However due to the book not being out for that long, not all pages have been translated.
The book is rather significant though all the fanon content, this book is truly what we can use to determine what is truly considered Canon. Such as the character’s appearance and other features however weird the results may be. Such as Nitori or Hina having high danger rates and fairly low human relationship rates. Or other features depicted in the art such as Satori actually having breasts.
That being said, the wiki doesn’t have all the information that is in the book of course. So if I were you and had some extra cash, I’d order it if you actually knew Japanese. It’s definitely worth the read.