References:
  K.H. Rosen, Discrete Mathematics and Its Applications, 5th Edition, McGraw-Hill, 2003.
R. Johnsonbaugh, Discrete Mathematics, 5th Edition, Prentice Hall, 2000.
K.A. Ross and C.R.B. Wright, Discrete Mathematics, 4th Edition, Prentice Hall, 1999.
J.A. Dossey, A.D. Otto, L.E. Spence and C.V. Eynden, Discrete Mathematics, 4th Edition, Addison Wesley, 2002.