Mitchell, C.N.; Kersley, L.; Pryse, S.E.; Willson, C.A.; Heaton, J.A.T.; Cannon, P.S.; Rogers, N.C.: 'Imaging and modelling of the main ionospheric trough using radio tomography', IET Conference Proceedings, 1999, p. 192-195, DOI: 10.1049/cp:19990048
IET Digital Library, https://digital-library.theiet.org/;jsessionid=2h248j5b63naf.x-iet-live-01content/conferences/10.1049/cp_19990048