How to learn Cohen-Tannoudji's QM well? I am studying Cohen-Tannoudji's QM, and was puzzled for so many development materials behind the book. How should I go on?
 A: The Cohen-Tannoudji style of putting a large fraction of the contents on chapter Complements can indeed be off-putting, but it's normally well explained in the introductory parts. 
Basically, the core content of the chapters themselves is meant to be sufficient and self-contained, so you can (in principle) ignore all the Complements and consume only the 'regular' content, though that runs the danger of leaving a 'flat' impression of the material and not giving you enough applications and concrete cases to be truly useful.
On the other hand, reading all of the complements makes for a much more intensive learning curve than most courses (both instructor-led and self-taught) really require, and that time is probably better spent elsewhere. 
The usual recommendation is a compromise - just read one or two Complements on the applications that interest you the most, and leave the rest for a later pass, or for cases where you're unsure about core aspects of the chapter's material. The Complements are typically written to be independent of each other and you should be able to mix and match at your discretion. 
