Harmonization of PCR-based detection of intestinal pathogens: experiences from the Dutch external quality assessment scheme on molecular diagnosis of protozoa in stool samples. - Schuurs TA; Koelewijn R; Brienen EAT; Kortbeek T; Mank TG; Mulder B; Stelma FF; van Lieshout L; van Hellemond JJ (Clinical chemistry and laboratory medicine, 2018)