Muller, A.A.; Lucyszyn, S.: 'Properties of purely reactive Foster and non-Foster passive networks', Electronics Letters, 2015, 51, (23), p. 1882-1884, DOI: 10.1049/el.2015.1429
IET Digital Library, https://digital-library.theiet.org/;jsessionid=9lj78l0766u09.x-iet-live-01content/journals/10.1049/el.2015.1429