Main sources: FC2 web gallery and pixiv
Bkub's assortment of Touhou art and comics, mainly in the 4koma format, starting in earnest from April of 2008. These frequently involve a strangely cute and quiet Chen and occasionally other characters such as Yakumo Yukari, Yakumo Ran, Inaba Tewi and Nazrin.
There are a few bkub Touhou comics that differ in art style and content from these. (e.g. standard chibi characters are drawn non-chibi or vice-versa; style differs from the rest of the pool.) These should not be in the pool unless they are confirmed as being done by bkub or as being part of the same books from which the other strips in the pool are taken.
There are separate pools for bkub's various Touhou books:
Currently, the order is based on both the release order (using his pixiv and the respective doujin releases) and the order in which they are shown on his FC2 web gallery (which includes comics and 4koma from the previously mentioned series). If you have a better idea of the order they should go in, please feel free to help fix it. Arguments can be made for the removal of those comics which appear in the other pools.