"Free textbooks and other open educational resources gain popularity," Physics Today 76 (7), 18–21 (2023)

"The prices of college textbooks have skyrocketed: From 2011 to 2018, they went up by 40.6% in the US, according to the Bureau of Labor Statistics’ Consumer Price Index. That can add up to as much as $1000 for a single semester. So it’s no surprise that freely available, openly licensed textbooks, lectures, simulations, problem sets, and more—known collectively as open educational resources (OERs)—are having a moment."