J. Fetzer, S. Kurz, G. Lehner, and W. Rucker. Proceedings of the 7th International IGTE Symposium on Numerical Field Calculation in Electrical Engineering, page 336-340. Graz, (1996)
V. Rischmüller, S. Kurz, and W. Rucker. Proceedings of the 9th International IGTE Symposium on Numerical Field Calculation in Electrical Engineering, Graz, (2000)