1. in Proceedings of the 1980 Erice Summer school (to appear).
2. ?Schr�dinger Operators with Electric or Magnetic Fields,? in Mathematical Problems in Theoretical Physics, Lecture Notes in Physics, Ed. (Springer, Berlin, Heidelberg, New York, 1980), Vol. 116.
3. Proceedings of the 1980 Seminario Matematico e Fisico della Universit� e del Politecnico di Milano (to appear).
4. and (unpublished).
5. The mathematical theory of resonances whose widths are
exponentially small