1. Mailloux, R.J.: ‘Hybrid antennas’, Rudge, A.W., Milne, K., Olver, A.D., Knight, P., Handbook of antenna design, (Peter Perigrinus, London 1982), p. 415–463 IEE electromagnetic wave series
2. Brown, J.: Microwave lenses, (Methuen & Co Ltd, London 1953),Chap. VI,