D. Kusnezov, A. Bruder, V. Ionescu, J. Kern, M. Rast, K. Heyde, P. Van Isacker, J. Moreau, M. Waroquier, R.A. Meyer Helvetica Physica Acta 60 (3), 456-4631987A1Published while none of the authors were employed at the CMMAbstract WOS:A1987H235400005DOI http://dx.doi.org/