1. Adobe Systems, Inc. 1999, PostScript Language Reference Manual, Third ed. (Addison-Wesley Publishing Company, Inc.), Reading, Massachusetts (see especially pages 293-296)
2. Representations of celestial coordinates in FITS
3. Calabretta, M. R., et al. 2003, Representations of distortions in FITS world coordinate systems, in preparation, Paper IV
4. Zur Elektrodynamik bewegter Körper