T. Buhl, B. Gregor Wienrich, C. Sieblist, M. P. Schön, and C. S. Seitz, “Development of Segmental Superficial Actinic Porokeratosis during Immunosuppressive Therapy for Pemphigus Vulgaris”, Acta Derm Venereol, vol. 90, no. 2, pp. 212–213, Feb. 2010.