Nielsen, E. MPI for Aeronomy, Max Planck Institute for Solar System Research, Max Planck Society; Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society;
Poulter, E. M., & Nielsen, E. (1982). The hydromagnetic oscillation of individual shells of the geomagnetic field. Journal Geophysical Research, 87, 432.