transvaginal ultrasound in the diagnosis of acute appendicitis: an observational study.. Ultrasound Obstet Gynecol. Mar 2003, 21 (3): 273–6. PMID 12666223
of infertility in patients with celiac disease: a meta-analysis of observational studies. Arq Gastroenterol (Meta-Analysis. Review). 2014, 51 (2): 144–50
1086/342270 . Wood, B. E.; Linsky, J. L.; Müller, H.-R.; Zank, G. P. Observational estimates for the mass-loss rates of α Centauri and Proxima Centauri
Islamic scientific tradition, particularly in the creation of experimental techniques." p. 465: "only when the influence of ibn al-Haytam and others on the