1. Ch. de la Vaissière:Nuovo Cimento,11 A, 185 (1972).
2. Chan-Hong Mo, J. Łoskiewicz andW. W. M. Allison:Nuovo Cimento,57 A, 93 (1968).
3. J. Debray: Ph. D. Thesis, Paris University (1970), unpublished.
4. T. P. Yiou: Ph. D. Thesis, Orsay University (1970), unpublished.
5. Ch. de la Vaissière: Ph. D. Thesis, Paris University (1970), unpublished.