There seem to be myriad of books written by B. K. S. Iyengar.
There's only 1, singular book, written by Sri K. Pattabhi Jois. 1.
There are some Iyengar-centric blogs out there, but really in the vastness of the blog-sphere very, very, limited (based on my searches). Ashtanga-centric blogs, on the other hand, there is certainly no shortage.