Direct product of groups (External and Internal). Isomorphism theorems - Diamond isomorphism theorem, Butterfly Lemma, Conjugate classes, Sylows theorm, p- sylow theorem .
Links:
[1] https://maths.iisuniv.ac.in/courses/subjects/advanced-abstract-algebra-3
[2] https://maths.iisuniv.ac.in/academic-year/2015-2016