The Economy (http://www.core-econ.org/the-economy/index.html) is an Open Access online course in economics. Throughout the course, authors start with a question or a problem about the economy and then teach the tools of economics that contribute to an answer.
2. Lindsay McKenzie. 2018. Open-Access Best Sellers.
Inside Higher Ed. https://www.insidehighered.com/news/2018/06/01/most-popular-open-access-monographs
As downloads of free scholarly books soar, what’s getting read?