Jaeglé, L., C. R. Webster, R. May, D. Fahey, E. L. Woodbridge, E. R. Keim, R. Gao, M. Proffitt, R. Stimpfle, R. Salawitch, S. C. Wofsy, and L. Pfister (1994), In Situ Measurements of the NO2/NO Ratio For Testing Atmospheric Photochemical Models, Geophys. Res. Lett., 21, 2555-2558.