Journal article (2002) - J Brakels (author), Els Els Van Daalen (author), MJJM van de Ven (author), W. Dik (author), S.M. Dopper (author), C Lohman (author), A.J. van Peppen (author), SG Peerdeman (author), DJ Peet (author), E. Sjoer (author), Willem van Valkenburg (author)