I'm not sure what the problem is, but according to this Chronicle report, "some producers of free e-textbooks have had trouble persuading professors to adopt them." It's the sort of story the Chronicle loves. So they report with glee "one backer of 'open-source textbooks' has decided to sell its titles on Chegg, an online textbook retailer, for a small fee in hopes of reaching a wider audience." I'm not sure exactly how charging money will increase readership. We're supposed to believe the problem is that "few professors have heard of the Twenty Million Minds Foundation or of OpenStax College, the Rice University-run service that hosts the free textbooks produced by the foundation." To me that says the problem is with the professors, not the books. No surprise, that.