1. Marcuvitz, N.: The waveguide handbook, (McGraw-Hill 1951), p. 387
2. Clarricoats, P.J.B., and Chambers, D.E.: ‘Backward wave propagation in non-periodic waveguide structures’, Proceedings of URSI symposium on electromagnetic theory and antennas, (Pergamon Press (to be published)
3. Clarricoats, P.J.B., and Birtles, A.B.: ‘Circular waveguide backward-wave experiments’, J. Electronics and Control, (to be published)