Advanced Modern Algebra: Third Edition, Part 2 ... -

Introduces homological algebra and its applications to groups:

Presentations, the Nielsen-Schreier theorem, and the Kurosh theorem. Chapter C-2: Representation Theory Advanced Modern Algebra: Third Edition, Part 2 ...

Structural analysis of these group types. Projective Groups: Simplicity of and projective unimodular groups. the Nielsen-Schreier theorem