06. Scotto J, Cotton G, Urbach F, Berger D, Fears T: Biologically effective ultraviolet radiation: Surface measurements in the United States, 1974 to 1985. Science 1988;239:762-764.

06. Scotto J, Cotton G, Urbach F, Berger D, Fears T: Biologically effective ultraviolet radiation: Surface measurements in the United States, 1974 to 1985. Science 1988;239:762-764.