2Lim JL, Stern RS. High levels of ultraviolet B exposure increase the risk of non - melanoma skin eaneer in psoralen and ultraviolet A - treated patients. J Invest Dermatol 2005 ; 124: 505 - 513.
3Kreimer- Erlacher H, Seidl H, Back B, et al. High mutation frequency at Ha - ras exons 1 - 4 in squamous cell carcinomas from PUVA- treated psoriasis patients. Photochem Photobiol 2001;74: 323 - 330.
4Nijsten TE, Stern RS. Oral retinoid use reduces cutaneous squamous cell carcinoma risk in patients with psoriasis treated with psoralen UVA: a nested cohort study. J Am Acad Dermatol 2003;49:644 650.
