- PyQGIS Cookbook (in developmemt)
- Book: The PyQGIS Programmer's Guide
- SourcePole GeoAPIs reference (a little out of date now)
- PyQGIS API documents
- An Introduction to Classes and Inheritance
- Intermediate Python Book
- Tips and Tricks
- PyQGIS3 Questions on gis.stackexchange.com watch out for answers by Ndawson, Nathan W, Underdark and other QGIS experts.