April 2013 – Klein Hofmeijer- Sevink M, van Oppen P, van Megen HJ, Batelaan NM, Cath DC, van der Wee NJ, van den Hout MA & van Balkom AJ. Clinical relevance of comorbidity in obsessive compulsive disorder: The Netherlands OCD Association study. Journal of Affective disorders 2013, April 15.