Published in a book of History of geomagnetism and aeronomy, Solar varibility and Geomagnetism,lectures from the IAGA Assembly in Hanoï 2001, collected and edited by W. Schröder, pp 154-190, Science edition AKGGKP, Bremen-Rönnebeck, Postdam, 2002.
On the electric current systems in the Earth's environment some historical aspects. Part II : external part/ ionosphere/ disturbed variation