http://www.digikey.com/us/en/techzone/microcontroller/resources/articles/protecting-inputs-in-digital-electronics.html
http://eagleup.wordpress.com/
http://www.instructables.com/id/Adding-Custom-Graphics-to-EAGLE-PCB-Layouts/step5/Configure-Import-Options-and-Click-OK/
http://rs20.mine.nu/w/2013/02/using-mosfets-as-blocking-diodes-reverse-polarity-protection/
