Dynamics of the mesosphere and lower thermosphere as seen by MF radars and by HRDI/UARS, B. Khattatov, M. Geller, V. Yudin, P. Hays, W. Skinner, M. Burrage, S. Franke, D. Fritts, J. Isler, A. Manson, C. Meek, R. McMurray, W. Singer, P. Hoffmann, R. Vincent, J. Geophys. Res. 101, 10,393-10,404, 1996.