Altadill, D., E. M. Apostolov, J. Boska, J. Lastovicka, and P. Sauli. “Planetary and Gravity Wave Signatures in the F-Region Ionosphere With Impacton Radio Propagation Predictionsand Variability”. Annals of Geophysics, vol. 47, no. 2-3 Sup., Dec. 2004, doi:10.4401/ag-3288.