Urgent endoscopy is associated with lower mortality in high-risk but not low-risk nonvariceal upper gastrointestinal bleeding - Lim, L. G.; Ho, K. Y.; Chan, Y. H.; Teoh, P. L.; Khor, C. J. L.; Rajnakova, A.; Ong, T. Z.; Yeoh, K. G. (Endoscopy, 2011)