Perusall (https://perusall.com/) is an e-book platform with collaborative annotation that aims to keep students on track before class. Perusall is free. Perusall is developed at Harvard by Gary King, Brian Lukoff, and Eric Mazur
See presentation about Perusall by Gary King: http://gking.harvard.edu/files/gking/files/ph.pdf
Perusall in Physics: https://www.youtube.com/watch?v=KnyWYGMT9A8&feature=youtu.be
Experiences RUG Groningen:
Download Flyer Werven voor het Grassrootsprogramma Perusall - FNWI
Original author: Natasa Brouwer