by (USSR)B.N.Srivastava;by (United Kingdom)M.Springford; by (USSR)H.M.Srivastava;by (United Kingdom)K.Rektorys; by (USSR)M.L.Krasnov;by (United Kingdom)L.M.Delves; by (USSR)A.Starkov;by (United Kingdom)A.Sharp; by (USSR)A.Yariv;by (United Kingdom)J.M.Ziman; by (USSR)A.Y.Lebedeva;by (United Kingdom)R.Courtney; by (India)R.Srinivasan;by (United Kingdom)M.M.Woolfson; by (USSR)A.A.Logunov;by (United Kingdom)W.Heisenberg; by (USSR)G.A.Sudzilovstij;by (United Kingdom)P.R.Webb; by (USSR)A.S.Kompaneyets;by (United Kingdom)E.Leader;