ZHANG, Ruda December 30, 2018:  Use dollar style math markup. [1b7036c]
ZHANG, Ruda December 02, 2018:  More on SVD, graph mining, Monte Carlo in econometrics, commercial satellite imagery; text formatting/reflow. [20eea16]
Ruda Zhang October 29, 2016:  Documenting OSM tools [eb22db2]
Ruda Zhang October 24, 2016:  epsg:3857 vs World Mercator epsg:3395; qgis expressions [e9199cd]
Ruda Zhang October 23, 2016:  Add world Mercator EPSG code. [7343ab4]
Ruda Zhang October 23, 2016:  Web mapping commerical player. [8c04d15]
Ruda Zhang October 18, 2016:  Definition of Mercator [c2b5e0b]