fdtd books
The Finite Difference Time Domain Method for Electromagnetics, Karl S. Kunz and Raymond J. Luebbers, CRC Press, Boca Raton, FL, 1993.
Computational Electrodynamics: The Finite-Difference Time-Domain Method, Allen Taflove, Artech House, Boston, MA, 1995.
Computational Electrodynamics: The Finite-Difference Time-Domain Method, 2 ed., Allen Taflove and Susan Hagness, Artech House, Boston, MA, 2000.
Computational Electrodynamics: The Finite-Difference Time-Domain Method, 3 ed., Allen Taflove and Susan Hagness, Artech House, Boston, MA, 2005.
Advances in Computational Electrodynamics: The Finite-Difference Time-Domain Method, Allen Taflove, Ed., Artech House, Boston, MA, 1998.
Electromagnetic Simulation Using the FDTD Method, Dennis Sullivan, IEEE Press, New York, 2000.
Time-Domain Computer Analysis of Nonlinear Hybrid Systems, Wenquan Sui, CRC Press, Boca Raton, FL, 2001.
Complex Electromagnetic Problems and Numerical Simulation Approaches, Levent Sevgi, IEEE Press and John Wiley, New York, 2003.
You can find these books on the website of Amazon.