Two-sided Meshes, Normal & Shininess – Blender Knowledgebase
Blender Quick Tip: Double-Sided Textures In Blender - YouTube
How to Create a Double-Sided Material in Blender - Lesterbanks
Is it better to have models that have double faces or is it better to have a two-sided material instead? - Pipeline & Plugins - Epic Developer Community Forums
How to use PBR Textures in Blender | cgbookcase.com