Oliveros-Rodríguez, Henry Oliverosa, and Édgar Beltrán Linares. 2012. “Preoperative Hemoglobin Levels and Outcomes in Cardiovascular Surgical Patients; Systematic Review and Meta-Analysis”. Colombian Journal of Anesthesiology 40 (1):27-33. https://www.revcolanest.com.co/index.php/rca/article/view/861.