http://www.circuitcellar.com/library/print/1105/Levinn-184/Levin-184.pdf http://www.circuitcellar.com/library/print/0106/Wotiz-186.pdf http://www.circuitcellar.com/library/print/0306/Leland-188/Leland-188.pdf http://www.circuitcellar.com/library/print/0906/Smith194/Smith-194.pdf
