EdTech Books: Completely Free Textbooks by various authors
Foundations of Learning and Instructional Design Technology by Richard West
The K-12 Educational Technology Handbook by Royce Kimmons
Project Management for Instructional Designers by David Wiley et al.
Qualitative Inquiry in Daily Life by David Williams
An Open Education Reader by David Wiley
Psychological Science by Mikle South, assisted by IPT alum Cristina Catron