Hirayama, Hiroshi: 'Basic theory of resonance coupling WPT' (Energy Engineering, 2018), 'Wireless Power Transfer: Theory, technology, and applications', Chap. 3, pp. 23-36, DOI: 10.1049/PBPO112E_ch3
IET Digital Library, https://digital-library.theiet.org/;jsessionid=ef4cff8la4krc.x-iet-live-01content/books/10.1049/pbpo112e_ch3