Hulleberg, G., Aamodt, A., Espehaug, B., & Benum, P. (2008). A clinical and radiographic 13-year follow-up study of 138 Charnley hip arthroplasties in patients 50–70 years old: Comparison of university hospital data and registry data. Acta Orthopaedica, 79(5), 609–617. https://doi.org/10.1080/17453670810016614