Warrington, E. M., Stocker, A. J., Zaalov, N. Y., Siddle, D. R. and Nasyrov, I. A. (2004) “Propagation of HF radio waves over northerly paths: measurements,simulation and systems aspects”, Annals of Geophysics, 47(2-3 Sup.). doi: 10.4401/ag-3292.