[Yaffs] something about yaffs for help

Hello everyone, I'm so happy to be joining this list and learn from you
guys.
It's been 1 month since I set my hand to yaffs file system, and i've been
reading source code recently, but i've got some problems in dealing with
the framework of yaffs and find it a little bit difficult in understanding
the codes, since the information and materials I read in past few days were
basically some rough introduction the principle.
May i have some recommendation from you guys of some websites, materials or
papers or whatever it is that are relatively professional and in detail?
Sourse codes with detailed notes would also be perfect.
Thanks a lot! LOL!