Closing holes in mesh - model 3D Blender - YouTube
8 Tips for Clean Topology in Blender (Updated for 2021) - CG Cookie | Learn Blender, Online Tutorials and Feedback
Grid Fill — Blender Manual
Blender 2.8 Three Ways of Filling Different Types of Holes | Hello everyone! This is a beginner's tutorial showing you different ways to close 3D model mesh holes using the new Blender
modeling - How to fill a rectangular hole with an even amount of vertices on either side? - Blender Stack Exchange