SPICE LINKS

http://www.uta.edu/ee/hw/pspice/
http://www.seas.upenn.edu/~jan/spice/spice.overview.html#Switches
http://ngspice.sourceforge.net/tutorials.html
http://ngspice.sourceforge.net/spices.html
http://ngspice.sourceforge.net/resources.html
http://www.cppsim.com/index.html
http://www.layouteditor.net/
http://www.geda-project.org/