Looking for three papers about filters

(1)A.E.Atia and A.E.Williams, " New type of waveguide bandpass filters for satellite transponders", COMSAT Tech.Rev, Vol.1, no.1, pp21-43,1971

(2)R.J.Cameron,"General prototype network synthesis methods for microwave filters",ESA J.,Vol.6, pp193-206,1982

(3)S.B.Cohn,"Direct-coupled-resonator filters",Proc.IRE, vol.45, pp187-196, February 1957