Citation: Baez, John C. "Spin networks in gauge theory." Advances in Mathematics 117.2 (1996): 253-272.
Web: https://arxiv.org/abs/gr-qc/9411007
Tags: Pedagogical, Mathematical, Physical
This is a wonderful introduction to spin networks, and their underlying gauge theory. The most important takeaway is the first line: "Penrose [14] introduced the notion of a spin network as an attempt to go beyond the concept of a manifold towards a more combinatorial approach to spacetime", with "[14]" being the reference
> Penrose, Roger. "Angular momentum: an approach to combinatorial space-time." Quantum theory and beyond 151 (1971).
As with everything Baez writes this article is very pedagogical, and is certainly the article to read on this subject.