I was searching for something else and couldn't stop reading. A bit on the heavy side in the way of explaining the topic, but none the less interesting for a dry topic.

http://www.uwasa.fi/~f76998/video/conversion/#4.7

As the title I used suggests, if you have trouble falling asleep, this ought to do the trick. Seriously, it is kind of interesting reading and makes a good attempt at trying to explain why things are as they are.