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Ansems, Sophie, Marjolein Berger, Patrick Ferry van Rheenen, Karin Vermeulen, Gina Beugel, Maria Couwenberg, und Gea Holtman. "Effect of Faecal Calprotectin Testing On Referrals for Children With Chronic Gastrointestinal Symptoms in Primary Care: Study Protocol for a Cluster Randomised Controlled Trial." BMJ Open 2021.

Ansems, Sophie, et al. "Effect of Faecal Calprotectin Testing On Referrals for Children With Chronic Gastrointestinal Symptoms in Primary Care: Study Protocol for a Cluster Randomised Controlled Trial." BMJ Open 2021.