http://www.asic-world.com/digital/combo3.html
http://www.youtube.com/watch?v=RZQTTfU9TNA
http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&ved=0CEEQFjAFOAo&url=http%3A%2F%2Fwww.psut.edu.jo%2Fsites%2FLogic%2FOld%2FLecture%252014.pps&ei=8mBJUMThDYvMrQfspYDwDA&usg=AFQjCNHsupcQxECKUEU0mHlXuLEiDifUhg&sig2=90zeA-m-rHXYw67ZPiJnPA
http://my.safaribooksonline.com/book/electrical-engineering/computer-engineering/9780750645829/chapter-5dot-combinational-logic-design-with-msi-circuits/126#X2ludGVybmFsX0ZsYXNoUmVhZGVyP3htbGlkPTk3ODA3NTA2NDU4MjkvMTI3
http://www.csie.nuk.edu.tw/~wuch/course/eea051/eea051-04.pdf
