Touloupakis, Georgios, et al. “Early-Stage Radiological Critical Analysis of Unsuccessful Cases Following a Four-Part Fracture Osteosynthesis of the Proximal Humerus: Focus on the ‘P’ Sign”. Acta Biomedica Atenei Parmensis, vol. 88, no. 2, Aug. 2017, pp. 178-84, https://doi.org/10.23750/abm.v88i2.5295.