| Visiting address | Universiteit van Amsterdam Faculty of Science Korteweg-de Vries Institute for Mathematics Room C3.132 Science Park 904 1098 XH Amsterdam The Netherlands |  |
| Postal Address | PO box 94248 1090 GE Amsterdam | |
| Telephone | +31 20 5258486 | |
| Telefax | +31 20 5257820 | |
| A.J.P.Heck@uva.nl |