Veneman, Jan F.; Lefeber, Dirk; Vitiello, Nicola: 'Review of exoskeletons for medical and service applications: ongoing Research in Europe on Wearable Robots, with focus on lower extremity exoskeletons' (Control, Robotics and Sensors, 2018), 'Wearable Exoskeleton Systems: Design, control and applications', Chap. 2, pp. 25-50, DOI: 10.1049/PBCE108E_ch2
IET Digital Library, https://digital-library.theiet.org/;jsessionid=2iw4jjei3ptx7.x-iet-live-01content/books/10.1049/pbce108e_ch2