'Introduction - thirst for energy' (Materials, Circuits and Devices, 2012), 'Fundamentals of Electromagnetic Levitation: Engineering sustainability through efficiency', Chap. 1, pp. 1-14, DOI: 10.1049/PBCS024E_ch1
IET Digital Library, https://digital-library.theiet.org/;jsessionid=m4htfqb5yiqe.x-iet-live-01content/books/10.1049/pbcs024e_ch1