1. Jacob Millman & Christos C. Halkias, Electronic Devices & Circuits, McGraw-Hill, 1967– Textbook
2. http://www.fmlink.com/article.cgi?type=Magazine&pub=Premises%20&%20Facilities%20Management&id= 30856&mode=source
3. http://www.circuitstoday.com/automatic-led-emergency-light 4.
4. http://www.ucl.ac.uk/estates/maintenance/fire/documents/UCLFire_TN_022.pdf 5.
5. http://en.wikipedia.org/wiki/Emergency_light.