Elementary Probability Theory - Digital Communication: Principles and System Modelling - page 217

References
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(2nd Ed.,)”, McGraw-Hill, 1987
2. Carlson, A.B., Crilly, P.B., Rutledge, J.C., “Communication Systems - An Introduction to
Signals and Noise in Electrical Communication (4th Ed.)”, McGraw-Hill International, 2002
3. Spiegel, M.R., “Schaum's Outline of Theory and Problems of Probability and Statistics”,
McGraw-Hill, 1998
4. http://mathworld.wolfram.com