A multipoint determination of the propagation velocity of a sudden commencement across the polar ionosphere.

Engebretson M.J., Murr D.L., Hughes W.J., Luhr H., Moretto T., Posch J.L., Weatherwax A.T., Rosenberg T.J., Maclennan C.G., Lanzerotti L.J., Marcucci F., Dennis S., Burns G., Bitterly J., Bitterly M. (1999) A multipoint determination of the propagation velocity of a sudden commencement across the polar ionosphere, Journal of Geophysical Research 104 (A10). 22433-22451;