Lacarrubba, Francesco, et al. “Double-Ended Pseudocomedones in Hidradenitis Suppurativa: Clinical, Dermoscopic, and Histopathological Correlation”. Acta Dermato-Venereologica, vol. 97, no. 6, Mar. 2017, pp. 763-4, doi:10.2340/00015555-2601.