need cavity filter paper

ALBERT E. Williams ALI E ATIA ?Dual－Mode Canonical Waveguide Filters?

Ji－Fuh Liang，Xiao－Peng Liang，Kawthar A. Zaki ，Ali E.Atia ?Dual－Mode Dielectric or Air－filled Rectangular Waveguide Filters?

Richard J. Cameron, ?Advanced Coupling Matrix Synthesis Techniques for Microwave Filters?

Thanks a lot!

I know it is not easy to find these articles,but I do need them!
Please help me!

You can find the 3-rd paper on the next address:
http://www.elektroda.pl/eboard/searc...mtt.html+paper