Free
- Unity Scripting API: https://docs.unity3d.com/ScriptReference/
- Stack Overflow: https://stackoverflow.com/
- Mixamo: https://www.mixamo.com/
- Textures: https://www.textures.com/library
- YouTube: https://www.youtube.com/
Paid
- Zenva Academy (Paid Courses): https://academy.zenva.com/