1. Käthel, Ch.: Phys. Rev. 73 (1948) 155.
2. Smit, J., Beljers, H.: Philips Res. Rept. 10 (1955) 113.
3. Belson, H.S., Kriessmann, C.J.: J. Appl. Phys. 30 (1959) 175 S.
4. Casimir, H.B.G., Smit, J., Enz, U., Fast, J.F., Wijn, H.P.J., Gorter, E.W., Duyvesteyn, A.J.W., Fast, J.D., De Jong, J.J.: J. Phys. Radium 20 (1959) 360.
5. Smit, J., Wijn, H.P.J.: Ferrites. New York and Eindhoven 1959.