AA.VV. “Callosities Due to Repeated Friction Unusual lesion. Folliculitis of the Buttock A.P.E.C. Acute Self-Healing Pustulosis”. European Journal of Pediatric Dermatology, vol. 9, no. 2, June 1999, pp. 93-8, https://ejpd.migration.pkpps03.publicknowledgeproject.org/index.php/journal/article/view/99.