Ross Gunn and B. B. Phillips, U. S. Weather Bureau AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF AIR POLLUTION ON THE INITIATION OF RAIN in: Journal of the Atmospheric Sciences 14, 1957, 272-280 Link: http://dx.doi.org/10.1175/1520-0469(1957)014<0272:AEIOTE>2.0.CO;2