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

http://www.digilentinc.com/classroom/realanalog/text/Chapter_2p6p1.pdf

http://books.google.com/books?id=IwhxyuqsuZIC&pg=RA1-PA389&lpg=RA1-PA389&dq=state+variable+%26+state+equation+in+electrical+circuit&source=bl&ots=fTAKGoYqzN&sig=7lQqQyL73ZXT9FWXtlluYsPrxj8&hl=fa&sa=X&ei=yIDAT7i7MJCa0QXI3sWZCg&ved=0CHMQ6AEwCQ#v=onepage&q=state%20variable%20%26%20state%20equation%20in%20electrical%20circuit&f=false

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

http://www.sml.ee.upatras.gr/UploadedFiles/StateFormulation.pdf

http://www.science.smith.edu/~jcardell/Courses/EGR326/RLC_SSModelIEEE.pdf

http://www.google.com/url?sa=t&rct=j&q=state+variable+%26+state+equation+in+electrical+circuit&source=web&cd=25&ved=0CGEQFjAEOBQ&url=http%3A%2F%2Fbungae.kaist.ac.kr%2Fcourses%2Ffall2007%2Fee484-ct%2Flm%2FState-variable%2520method%2C%2520standard-form%2520state%2520equations.ppt&ei=n4PAT6CNMufB0gWd7IyrCg&usg=AFQjCNGp_O3vTLKechr2I4rIlerDr98NAA

http://www.lucent.com/bstj/vol47-1968/articles/bstj47-9-1957.pdf

http://www.google.com/url?sa=t&rct=j&q=state+variable+%26+state+equation+in+electrical+circuit&source=web&cd=29&ved=0CHIQFjAIOBQ&url=http%3A%2F%2Fwww.site.uottawa.ca%2F~rhabash%2FELG3150LN03&ei=n4PAT6CNMufB0gWd7IyrCg&usg=AFQjCNGywSaujVV86pmzvW_dOC-a-wPfGQ