References

Wood, David, Bert Bates, Kathy Sierra, Brett D. McLaughlin, Gary Pollice, and David West. Head First Object-Oriented Analysis and Design: A Brain Friendly Guide to Object Oriented Programming. Cambridge: O'Reilly Media, Incorporated, 2006. Print.

"Abstraction (computer Science)." Wikipedia. Wikimedia Foundation, 18 Apr. 2014. Web. 25 Apr. 2014. <http://en.wikipedia.org/wiki/Abstraction_(computer_science)>

"Polymorphism (computer Science)." Wikipedia. Wikimedia Foundation, 25 Apr. 2014. Web. 25 Apr. 2014. <http://en.wikipedia.org/wiki/Polymorphism_(computer_science)>

"Inheritance (object-oriented Programming)." Wikipedia. Wikimedia Foundation, 21 Apr. 2014. Web. 25 Apr. 2014. <http://en.wikipedia.org/wiki/Inheritance_(object-oriented_programming)>.

"Encapsulation (object-oriented Programming)." Wikipedia. Wikimedia Foundation, 21 Apr. 2014. Web. 25 Apr. 2014. <http://en.wikipedia.org/wiki/Encapsulation_(object-oriented_programming)>