References:

Abstract Algebra - Wikipedia

https://en.wikipedia.org/wiki/Abstract_algebra

“Group theory, abstraction, and the 196,883-dimensional monster” - 3Blue1Brown

https://www.youtube.com/watch?v=mH0oCDa74tE

Axiomatic System - Wikipedia

https://en.wikipedia.org/wiki/Axiomatic_system

Axiom - Wikipedia

https://en.wikipedia.org/wiki/Axiom

Pure Mathematics - Wikipedia

https://en.wikipedia.org/wiki/Pure_mathematics

Group Theory - Wikipedia

https://en.wikipedia.org/wiki/Group_theory

Group (Algebra) - Wikipedia

https://en.wikipedia.org/wiki/Group_(mathematics)

Main Classes of Groups in Group Theory - Wikipedia

https://en.wikipedia.org/wiki/Group_theory#Main_classes_of_groups

Classification of Finite Simple Groups - Wikipedia

https://en.wikipedia.org/wiki/Classification_of_finite_simple_groups

Finite Group - Wikipedia

https://en.wikipedia.org/wiki/Finite_group

Lie-Type Group - Wolfram Mathworld

https://mathworld.wolfram.com/Lie-TypeGroup.html

Monster Group - Wikipedia

https://en.wikipedia.org/wiki/Monster_group

Monstrous Moonshine - Wikipedia

https://en.wikipedia.org/wiki/Monstrous_moonshine

J-invariant and Q-expansion - Wikipedia

https://en.wikipedia.org/wiki/J-invariant#The_q-expansion_and_moonshine

Continuous Symmetry - Wikipedia

https://en.wikipedia.org/wiki/Continuous_symmetry

Geometric Group Theory - Wikipedia

https://en.wikipedia.org/wiki/Geometric_group_theory