Online Documentation and Tutorials
Includes the "QGIS Training Manual" (with canned data and exercises, enough for a 5-day workshop!), and the concept-oriented "A Gentle Introduction to GIS"
Great content, much of it focused around examples with non-Roman character sets, and using other open source tools like LibreOffice
Also includes excellent installation instructions
Search the U-M Library Catalog for qgis to find books, both electronic and print, like this one:
Published in 2016, by Anita Graser. Available online to UM affiliates