Amazon.com: Blender 2.8X Introductory-Level Instructional Handout on How to Model and Animate a Sea Turtle: Proportional Editing and Parenting eBook : Samaniego MEd, Adriel: Kindle Store
Proportional Edit — Blender Manual
Weird bump when using proportional editing : r/blenderhelp
Custom Falloff for Proportional Editing - User Feedback - Developer Forum
Proportional editing in Blender tutorial - Artisticrender.com