Journal or Book Title
Transactions of the ASAE
Maps of mean wet-bulb temperature isolines and mean wet-bulb depression isolines (and their standard deviations) for the U.S. and southern Canada were drawn for each month of the year using weather data from 140 observing sites. Map isolines use degrees Celsius units.
American Society of Agricultural and Biological Engineers
Waite, Paul J. and Bern, Carl J., "Wet-Bulb Temperatures and Wet-Bulb Depressions in the United States and Southern Canada" (1987). Agricultural and Biosystems Engineering Publications. 453.