1. Hultqvist, B.: 1966, ‘Ionospheric absorption of cosmic radio noise’, Space Sci. Rev.
5, 771–817.
2. Akasofu, S.-I. Chapman, S., and Meinel, A. B.: 1966, ‘The aurora’, in Handbuch der Physik, Vol. XLIX-1 (ed. by S. Flügge), Springer-Verlag, Berlin, pp. 1–158.
3. Ansari, Z. A.: 1964, ‘The aurorally associated absorption of cosmic noise at College, Alaska’, J. Geophys. Res.
69, 4493–4513.
4. Ansari, Z. A.: 1965, ‘A peculiar type of daytime absorption in the auroral zone’, J. Geophys. Res.
70, 3117–3122.
5. Bailey, D. K.: 1968, ‘Some quantitative aspects of electron precipitation in and near the auroral zone’, Rev. Geophys.
6, 289–346.