According to a Google Scholar search conducted in September 2012 by the Institute of Optics of the University of Rochester, Prof. Taflove's Computational Electrodynamics: The Finite-Difference Time-Domain Method is the 7th most-cited book in physics, with an updated total of 16,446 Google Scholar citations as of Jan. 20, 2017.
The descriptors "finite difference time domain" and "FDTD" coined by Prof. Taflove in 1980 have since become widely used, having appeared in this exact form in approximately 100,000 and 195,000 Google Scholar search results, respectively, as of Jan. 20, 2017.