Kondo, Y., . Koike, H. Ikeda, B.E. Anderson, K.E. Brunke, Y. Zhao, K. Kita, T. Sugita, H.B. Singh, S.C. Liu, A.M. Thompson, G.L. Gregory, R.E. Shetter, G.W. Sachse, S. Vay, E. Browell, and M. Mahoney (1999), Impact of aircraft emission on NOx in the lowermost stratosphere at northern midlatitudes, Geophys. Res. Lett., 26, 3065-3068.