sao 3 : A traditional unit of land area in Vietnam. The sao varies somewhat from province to province. It is equal to 360 square meters (430.6 square yards) in many places, but as much as 500 square meters (598.0 square yards) in others
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}