Readability and Basic Course Hybrid Textbooks in Human Communication: A Disparity of Reading Difficulty - Schneider, David E. and Walter-Reed, Melissa (Communication Research Reports, 2009)
https://katalog.adlr.link/Record/ai-49-aHR0cDovL2R4LmRvaS5vcmcvMTAuMTA4MC8wODgyNDA5MDkwMzI5MzY3Ng