T. B. Leyser, F. Waldemarsson, and S. C. Buchert. Plasma angular momentum effects and twisted incoherent scatter radar beams. Radio Sci., volume 47, issue 5, 2012 . B. Gustavsson, R. Newsome, T. B. Leyser, M. J. Kosch, L. Norin, M. McCarrick, T. Pedersen, and B. J. Watkins. First observations of X-mode suppression of O-mode HF enhancements at 6300 A . Geophys. Res. Lett., volume 36, 2009 .