Transfusion guidelines in adult spine surgery: a systematic review and critical summary of currently available evidence. - Barrie, Umaru; Youssef, Carl A.; Pernik, Mark N.; Adeyemo, Emmanuel; Elguindy, Mahmoud; Johnson, Zachary D.; Ahmadieh, Tarek Y. El; Akbik, Omar S.; Bagley, Carlos A.; Aoun, Salah G. (Spine Journal, 2022)