Geomagnetic Field Variations - GlaÎ²meier, Karl-Heinz; Glabmeier, Karl-Heinz; Glassmeier, Karl-Heinz; Hutter, Kolumban; Negendank, Jörg F. W.; Soffel, Heinrich Christian; edited by Kolumban Hutter; Negendank, Jörg; Soffel, Heinrich (Springer Berlin Heidelberg, 2009)