Nickel, Ulrich: 'Introduction to real aperture array radar' (Radar, Sonar and Navigation, 2017), 'Novel Radar Techniques and Applications Volume 1: Real Aperture Array Radar, Imaging Radar, and Passive and Multistatic Radar', Chap. ptI, pp. 1-5, DOI: 10.1049/SBRA512F_ptI
IET Digital Library, https://digital-library.theiet.org/;jsessionid=3f6cqbh95j2hs.x-iet-live-01content/books/10.1049/sbra512f_pti