1. Kraus, J. D. (1988) Radio Astronomy, 2nd Edition, Cygnus.Quasar Books, Powell, Ohio.
2. Spaulding, A. D. & Hagn, G. H. (1978) Worldwide minimum radio noise levels (0.1 Hz to 100 Ghz), Effect of the ionosphere on Space and Terrestrial Systems, J. M. Goodwin, Ed., ONR7NRL, Arlington, VA, Jan. 24–26, 1978.
3. CCIR (1986b) Report 670, Worldwide external noise levels, 0.1 Hz to 100 GHz,Vol. 1, Spectrum Utilization and Monitoring, Recommendations and Reports of the CCIR, XVIth Plenary Assembly, Dubrovnik, 1986, ITU, Geneva.
4. Smith, E. K. (1982) The natural radio noise environment, Proc. IEEE Int’l Sympon EMC, Santa Clara, CA, Sept. 6–8, 1982., pp 266–277
5. CCIR (1986a) Report 720-2, Radio emission from natural sources in the frequency range above about 50 MHz, Vol. 5, XVI Plenary Assembly, Dubrovnik, 1986, ITU Geneva.