http://mail.vssd.nl/hlf/e008h06.pdf

http://www.atp.ruhr-uni-bochum.de/rt1/syscontrol/node66.html

http://www.google.com/url?sa=t&rct=j&q=phase+frequency+characteristic&source=web&cd=14&ved=0CFoQFjADOAo&url=http%3A%2F%2Fwnt.sjtu.edu.cn%2Fteaching%2Fchp5.ppt&ei=4Fm7T8HlOZCO4gSpytSkCQ&usg=AFQjCNHREfhL3jua7lI8r5s4Fx5oE0WZoQ

http://en.wikipedia.org/wiki/Low-pass_filter

http://www.allaboutcircuits.com/vol_2/chpt_8/2.html

http://en.wikipedia.org/wiki/High-pass_filter

http://www.science.unitn.it/~bassi/Signal/TInotes/sloa049.pdf

http://www.electronics-tutorials.ws/filter/filter_3.html

http://www.allaboutcircuits.com/vol_2/chpt_8/4.html

http://en.wikipedia.org/wiki/Band-pass_filter

http://www.ecircuitcenter.com/circuits/mfb_bandpass/mfb_bandpass.htm

http://www.allaboutcircuits.com/vol_2/chpt_8/5.html

http://electriciantraining.tpub.com/14181/css/14181_51.htm

http://www.circuitstoday.com/band-stop-filter

http://www.circuitstoday.com/band-stop-filter

http://earmark.net/gesr/opamp/wide_br.htm

http://en.wikipedia.org/wiki/Bode_plot

http://lpsa.swarthmore.edu/Bode/BodeRules.html

http://www.ece.utah.edu/~ee3110/bodeplot.pdf

http://www.seas.upenn.edu/~ese216/handouts/ExampleBodeDiagram.pdf

http://users.ece.gatech.edu/mleach/ece3040/notes/bode.pdf

http://lpsa.swarthmore.edu/Bode/BodeExamples.html

http://www.me.unm.edu/~starr/teaching/me581/FRexample.pdf

http://www.google.com/url?sa=t&rct=j&q=%D8%B4%D8%A8%DA%A9%D9%87+%D8%B3%D9%88%D8%AF%D9%87+%D8%AF%D8%B1+%D9%85%D8%AF%D8%A7%D8%B1%D9%87%D8%A7%DB%8C+%D8%A7%D9%84%DA%A9%D8%AA%D8%B1%DB%8C%DA%A9%DB%8C&source=web&cd=1&ved=0CEsQFjAA&url=http%3A%2F%2Fwww.pnu.ac.ir%2Fportal%2FFile%2FShowFile.aspx%3FID%3D244a4f98-11fe-418d-9a07-b795600d6cd2&ei=FYbUT9GfBM6S0QX2tZH_Aw&usg=AFQjCNEmT84o_rk05bW0GAGjLyIxl9gtPQ