Natural Earth is a public domain map dataset available at 1:10m, 1:50m, and 1:110 million scales. Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.
The EPSG Geodetic Parameter Dataset is a structured dataset of Coordinate Reference Systems and Coordinate Transformations, accessible through this data registry.
G. Altan, and Y. Kutlu. 2015 23nd Signal Processing and Communications Applications Conference (SIU), Institute of Electrical and Electronics Engineers (IEEE), (May 2015)