- H. Barendregt , Nijmegen, The Netherlands.

- H. Geuvers , Nijmegen, The Netherlands.

- I. Moerdijk , Utrecht, The Netherlands.

- J. van Oosten , Utrecht, The Netherlands.

- B. Spitters , Nijmegen, The Netherlands.

- W. Veldman, Nijmegen, The Netherlands.

- S.A. Terwijn, Utrecht, The Netherlands.