Chegireddy, Chinna Obula Reddy Ionospheric variability over tirunelveli during jan - 2008 Chinna Obula Reddy Chegireddy - Mumbai IIG 2014 - 25p. col.fig.;ill.;ref. M.Sc. Project report submitted under the guidance of Dr. Mala S. Bagiya Universal Decimal Class. No.: PR-047 / CHE