@article{articlee853aff0,
title   = {C-layer dependence on solar cycle and southern latitude observed by vlf propagation},
author = {Kuntz, V L R and Piazza, L R and Kaufmann, P},
year = {1991},
doi = {10.1016/0021-9169(91)90036-7},
journal   = {Journal of Atmospheric and Terrestrial Physics}
}