Validity evidence for endoscopic ultrasound competency assessment tools: Systematic review - Alessandra Ceccacci; Harneet Hothi; Rishad Khan; Nikko Gimpaya; Brian P.H. Chan; Nauzer Forbes; Paul James; Daniel Jeffry Low; Jeffrey Mosko; Elaine T. Yeung; Catharine M Walsh; Samir C Grover (Endoscopy International Open)