Wretenberg, Per, and Anders Ekelund. 1997. “Acute Hemiarthroplasty After Proximal Humerus Fracture in Old Patients: A Retrospective Evaluation of 18 Patients Followed for 2-7 Years”. Acta Orthopaedica 68 (2):121-23. https://doi.org/10.3109/17453679709003992.