Kenyon, G.H.: 'The Ground Window concept', IET Conference Proceedings, 2007, p. 107-122, DOI: 10.1049/ic.2007.1700
IET Digital Library, https://digital-library.theiet.org/;jsessionid=16ronni27pb7b.x-iet-live-01content/conferences/10.1049/ic.2007.1700