1. IV. Comparison of simultaneous magnetic disturbances at several observatories
2. On the asymmetric development of magnetic storm fields in low and middle latitudes
3. Akasofu S.-I., and Chapman S.,Solar Terrestrial Physics, Oxford University Press, Oxford, 1972.
4. Barlow J.L., Chapter 9: Numerical Aspects of Solving Linear Least Squares Problems. In Rao C.R.,Handbook of statistics – computational statistics, Amsterdam, London, New York, Tokyo, North Holland, p. 920, ISBN: 0-444-88096-8, 1993.
5. The three-hour-range index measuring geomagnetic activity