Inoue, Tomoko, et al. “Effective Oral Psoralen Plus Ultraviolet A Therapy for Digital Ulcers With Revascularization in Systemic Sclerosis”. Acta Dermato-Venereologica, vol. 94, no. 2, Aug. 2013, pp. 250-1, doi:10.2340/00015555-1678.