Jenner, L. A., A. G. Wood, G. D. Dorrian, K. Oksavik, T. K. Yeoman, A. R. Fogg, and A. J. Coster (2020), Plasma density gradients at the edge of polar ionospheric holes: the absence of phase scintillation, Annales Geophysicae, doi.org/10.5194/angeo-38-575-2020