Novak, Markus H.; Volakis, John L.: 'Ultra-wideband arrays' (Electromagnetic Waves, 2018), 'Developments in Antenna Analysis and Design: Volume 2', Chap. 9, pp. 287-322, DOI: 10.1049/SBEW543G_ch9
IET Digital Library, https://digital-library.theiet.org/;jsessionid=2qai7r2lt5vld.x-iet-live-01content/books/10.1049/sbew543g_ch9