http://www.cs.ucf.edu/~dmarino/ucf/cot3100h/lectures/COT3100BitwiseOps.pdf

http://web.ee.nchu.edu.tw/~cpfan/FY92b-digital/Chapter2.pdf

http://www.pbte.edu.pk/text books/dae/math_123/Chapter_11.pdf

http://bnrg.cs.berkeley.edu/~randy/Courses/CS150.F00/CLD2/chapter02.pdf