Yefim Gordon discussed both the project history, prototypes, technical details (From Fuselage, Landing gear, control System... etc, basically everything), and a little bit about Russian's next-generation fighter's prospect and how US fighter projects affects Russian.In sum, it's a good book. However, my friend (who is a die-hard fan of Russian aviation) told me that if you are already familiar with these two projects, you won't get anything new out of it except nice pictures. Personally I am very satisfied because I need a reference like this. So whether this book is for you will depend on how will you know Russian fighter projects.
RedStar1 - Sukhoi S-37 and Mikoyan MFI - Russian Fifth-Generation Fighter Demonstrators