Toffoli[0] & Margolus’[1] Cellular Automata Machines (1987) is the CA bible, I guess. Andrew Adamatsky edited the encyclopedic Cellular Automata (2018). Ed Fredkin's[2] stuff on reversible CA is fascinating. Gerard Vichniac[3] wrote some great papers in the 80s, e.g. Simulating Physics with Cellular Automata (1984). Kenichi Morita[4] papers. Rudy Rucker[5] has written a lot of stuff on 1 and 2D CA, and worked as a CA programmer. Etc. There are a lot of papers. The very common finite element method of solving differential equations and PDEs is basically the same thing as CA - see e.g. Anderson's Computational Fluid Dynamics.

Attractors and approximations for lattice dynamical systems by Shengfan Zhou, 2002.

1954's Studies of Nonlinear Problems by Fermi, Ulam, Pasta, featuring a 1D CA. https://www.cs.princeton.edu/courses/archive/fall02/cs323/li...

Noether's theorem comes up frequently - that every symmetry of the system corresponds to a conservation law.[6]

Smooth Life is Stephan Rafler's very cool version of CGOL with every discrete aspect turned into a continuous one.[7]

[0] https://en.wikipedia.org/wiki/Tommaso_Toffoli

[1] https://people.csail.mit.edu/nhm/ https://en.wikipedia.org/wiki/Norman_Margolus

[2] https://en.wikipedia.org/wiki/Edward_Fredkin

[3] https://scholar.google.com.au/scholar?as_vis=1&hl=en&q=gerar...

[4] https://scholar.google.com/citations?user=kujUxFYAAAAJ&hl=en

[5] https://en.wikipedia.org/wiki/Rudy_Rucker

[6] https://en.wikipedia.org/wiki/Noether%27s_theorem

[7] best video of SmoothLife https://www.youtube.com/watch?v=KJe9H6qS82I

https://sourceforge.net/projects/smoothlife/files/

This slideshow by Rafler contains the best, most complete explanation of it I've found: https://www.youtube.com/watch?v=iyTIXRhjXII

Shadertoy version https://www.shadertoy.com/view/XtdSDn