1. E. Butkov, Mathematical Physics, Addison-Wesley, 1966. Treats orthogonal functions and theory of distributions
2. A. Crewe et al., “A Scanning Electron Microscope,” Scientific American, March 1971.
3. E. Horowitz, “A General Field-Line Plotting Algorithm,” Computers in Physics, July/August 1990, p. 418.
4. J. Jackson, Classical Electrodynamics, Wiley, 1962
5. H. Kober, Dictionary of Conformal Representations, Dover, 1957