http://w1.859.telia.com/~u85920178/use/ssb-filt.htm
Principles in choosing filter parameters.
http://www.electronics-tutorials.com/filters/if-amplifier-filters.htm
By D. B. Leeson. Introductory guide to using 1/8 wavelength stubs in lowpass, bandpass, and bandstop microwave filters. Also briefly discussed are 1/4 wavelength coupled-line filters, interdigital filters, comb-line filters, impedance matching filters, di
http://home.sandiego.edu/~ekim/e194rfs01/filterek.pdf
General techniques used in microstrip and stripline filter design. Covers low-pass, bandpass, and bandstop filters. Briefly covers coupled-line, interdigital, and comb-line filter structures, as well as the Dishall tuning method.
http://www.acusd.edu/~ekim/e194rfs01/filterek.pdf
for the 9, 6 and 3cm bands
http://www.mrs.bt.co.uk/dubus/8601-2.pdf
http://www.mrs.bt.co.uk/dubus/8504-2.pdf
http://www.mrs.bt.co.uk/dubus/8901-1.pdf