Thompson, R. J. Ionospheric variability in the Australian Region / [by] R.J. Thompson. - Chatswood, N.S.W. : IPS Radion and Space Services, 1990. - 41 p. - IPS Radio and Space Services Report ; IPS TR-90-01 . ISSN: 0812-7395 Subjects--Topical Terms: Ionosphere--Observations.Sudden ionospheric disturbances.