Datum Pro
- http://www.geomatix.net/datumpro
- Windows program which converts between map datums and projections, including Gauss Kruger, TM, UTM, and Lambert Conic grids.
James Q. Jacobs - Geodesy Page
- http://www.jqjacobs.net/astro/geodesy.html
- Definitions relating to geodesy, explanations of coordinate systems, and geodesy formulas. Reference ellipsoid defined with derived geometrical constants, equation of the meridional ellipse, and geometry of the meridian section.