You are welcome to propose additional items to this colletion of links:
Crystallography
Crystallographic point group (Wikipedia)
Defects in Crystals: H. Föll, 2019
Design, Science and Art: R. Takaki (in Japanese)
Escher-like Tessellations: Original tessellations by David Bailey, 2009
GAP package Cryst: Computing with crystallographic groups
GAP package Carat: Interface to CARAT, a crystallographic groups package
GAP package CrystCat: The crystallographic groups catalog
Genetic Code’s Symmetries: 2014
GeoGebra
M. C. Escher Collection
Math and Art of M. C. Escher
Noether Symmetries: 2022
Symmetry and Symmetry Breaking (Stanford Encyclopedia of Philosophy): K. Brading, 2017
Symmetry Artist
Symmetry: Dimensions of Particle Physics
Symmetry, Integrability and Geometry: Methods and Applications (SIGMA)
Symmetries of Particles
Symmetry Resources at Otterbein University
Symmetry (The Cambridge Crystallographic Data Centre)
Symmetry (Wikipedia)
The principle of symmetry in graphic design