The Online Encyclopaedia of Mathematics is the most up-to-date and comprehensive English-language graduate-level reference work in the field of mathematics today. This online edition comprises more than 8,000 entries and illuminates nearly 50,000 notions
On-line dictionary with multiple languages: german, english, french, italian, spanish, portuguese, dutch and swedish. Also has unit conversion calculators etc.
This chronology covers period starting from Perrin and Roentgen discoveries in 1895 up to the 1995 evidence of the top quark from FNAL, and is continuously maintained up to date. Has links to many historic papers.
The GPS precise orbits are derived using 24 hour data segments from the global GPS network coordinated by the International GPS Service (IGS). Provides links to coordinate transformation (geoid) computations and to the continuously operating [GPS] reference stations.