http://en.wikibooks.org/wiki/Circuit_Theory/First_Order_Circuits

http://www.ece.ubc.ca/~shahriar/eece251_notes/eece251_set4_2up.pdf

http://ocw.nthu.edu.tw/ocw/upload/12/239/07handout.pdf

http://www.ece.mtu.edu/faculty/goel/EE-2110/Prob-7.pdf

http://ee.lamar.edu/EELABS/ELEN2107/Lab6.pdf

http://ee.lamar.edu/eelabs/elen2107/lab5.pdf

http://ptuece.loremate.com/pulse-and-digital-switch-circuits/node/2

http://claymore.engineer.gvsu.edu/~johnsodw/egr314/paper.html

http://www.eee.metu.edu.tr/~ccandan/ee202/EE202_Spring201011/leaky_integrator_RC_circuit.pdf

http://physics.nyu.edu/~physlab/Misc_Labs/RCCircuit.pdf

http://www.utdallas.edu/~tbhatt/EE%203101/LABS/exp6.pdf

http://eelab.sjtu.edu.cn/dl/pps/chapter%207.pps

http://ixil.izt.uam.mx/~egum/Bi215101017/index_files/NILSS_07.pdf

http://books.google.com/books?id=7nNjaH9B0_0C&pg=PA354&lpg=PA355&ots=bri4zbjaBi&dq=exercise+for+response+of+one+order+circuits#v=onepage&q=exercise%20for%20response%20of%20one%20order%20circuits&f=false