Show 10 5 10 15 20 50 100 250 Sort by year (new to old) Actions Download search results Subscribe to news feed Your filters: cql: author="De graaf, Erik AB" or (type exact bookEditor and editor="De graaf, Erik AB") Add to list Journal Article A1 Assessment of prevalence of persons with down syndrome: a theory-based demographic model Gert De Graaf, Jeroen C Vis, Meindert Haveman, Geert Van Hove (UGent) , Erik AB De graaf, Jan GP Tijssen and Barbara JM Mulder (2011) JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES. 24(3). p.247-262