Never having done this before, now seemed like a good idea to give it a try.
I entered eCampusOntario's Open Textbook Library and searched for textbooks on Project Management. The search tool is good, a general text on the topic appeared at the top of the list, followed by other texts that focus on specific areas of project management. The license information was clear and used one of the icons that we learned about in an earlier module. I was surprised to see that the text is available in about 10 different formats, some of them editable, some optimized for reading or printing.
One of the formats is XML, which I find fascinating, but decided to leave for another day. I selected the .odt format (open document text) because it (sort of) looked like something I could work with. It turns out that ODT is a VERY rich rich text format similar to MS Word. The text opened easily in Word and the formatting is sophisticated with styles, navigation tied to the table of contents and chaptering, etc. It was clearly designed with adaptation in mind.
I do not know if I want to actually use this text in my course, but this was a rewarding afternoon of discovery.