Lubrano di Scorpaniello, E., and A. Spadaro. “Unmet Needs in Outcome Measures of Psoriatic Arthritis: Focus on Axial Radiographic and Nail Involvement”. Acta Biomedica Atenei Parmensis, vol. 84, no. 2, Sept. 2013, pp. 87-93, https://www.mattioli1885journals.com/index.php/actabiomedica/article/view/2733.