add more links

Author: danabauer

data-sources.md

@@ -3,7 +3,9 @@
 ### Public imagery
 * [USGS Earth Explorer](https://earthexplorer.usgs.gov/): 40 years of Landsat data and much, much more
 * [European Space Agency: Sentinel-2](http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-2): Data and imagery from the European Commission’s Copernicus programme
+* [NASA's Reverb Data Hub](https://reverb.echo.nasa.gov/reverb/#utf8=%E2%9C%93&spatial_map=satellite&spatial_type=rectangle): Aqua, Terra, Aura, TRMM, Calipso, NASA DC, JASON, ENVISAT, ALOS, METEOSAT, GOES, ICESAT, GMS, Landsat, NIMBUS, SMAP, RADARSAT, NOAA satellites, GPS satellites, and more...
 * [AWS Public Data Sets](https://aws.amazon.com/public-datasets/): Landsat, Sentinel-2, MODIS, Terrain Tiles, and more
+* [More sources here](http://gisgeography.com/free-satellite-imagery-data-list/): Go crazy. 
 
 ### Commercial imagery from Planet and other sources
 * [Planet Explorer](https://www.planet.com/explorer/): Browse satellite imagery captured over time, all around the world