1. Bradley, P., Kutiev, I., Muhtarov, P. Day-to-day variability of the basic MUF. in: Hanbaba, R., de la Morena, B. (Eds.), COST 251/Workshop on Procedures and Testing of the Models for Ionospheric Telecommunications Application. Universidad de Huelva, El Arenosillo, Spain, pp. 133–156, 1999
2. Introduction to Geomagnetic Fields;Campbell,1997
3. Davis, R.M., Groome, N.L. Variations of the 3000 km MUF in time and space. Nat. Bur. Stds. Tech. Report 8498. US Government Printing Office, Washington, DC, 1964
4. Hanbaba, R. COST-251 final report. Space Research Centre, Warsaw, Poland, Hanbaba, pp. 146–147, 1999
5. Performance prediction methods of HF radio systems;Hanbaba;Annali di Geofisica,1998