C++ dot vs arrow
http://www.tutorialspoint.com/cplusplus/cpp_member_operators.htm
C++ pointer vs reference
http://www.ntu.edu.sg/home/ehchua/programming/cpp/cp4_PointerReference.html
http://stackoverflow.com/questions/114180/pointer-vs-reference
http://stackoverflow.com/questions/57483/what-are-the-differences-between-
pointer-variable-and-reference-variable-in-c