https://www.cambridgeinternational.org/Images/285026-topic-3.4.2-virtual-machine-9608-.pdf
http://www.bbc.co.uk/education/guides/zgmpr82/revision/3
http://www.ni.com/white-paper/8708/en/
http://www.careerbless.com/java/basics/JavaArchitecture.php
http://www.cs.mtu.edu/~zlwang/virtualmachines/slides/Introduction.ppt