Matsuki, Y., K. Takakura, and K. Shigemi. “General Anesthesia and Intraoperative Opioids Do Not Affect Postoperative Delirium in Femoral Neck Surgery”. Anaesthesia, Pain & Intensive Care, Jan. 2019, pp. 372-5, https://mail.apicareonline.com/index.php/APIC/article/view/345.