1. Carrier Phase Recovery for Two Dimensional Digital Communications
2. R W Lucky, J Salz & E J Weldon, Jr,Principles of data communication.McGraw-Hill, New York, 1968.
3. W C Lindsey,Synchronous systems in communication and control.Prentice-Hall, Englewood Cliffs, NJ, 1972.
4. A J Veterbi,Principles of coherent communication, McGraw Hill, New York, 1966.