"Using Multimedia for E-Learning" (article)Mayer, R. E. (2017). Using multimedia for e-learning. Journal of Computer Assisted Learning, 33(5), 403–423. https://doi.org/10.1111/jcal.12197
This paper reviews 12 research-based principles for how to design computer-based multimedia instructional materials to promote academic learning, starting with the multimedia principle (yielding a median effect size of d = 1.67 based on five experimental comparisons), which holds that people learn better from computer-based instruction containing words and graphics rather than words alone.
Learning Web Design by 
E-Learning and the Science of Instruction by 