Martín Ezquerra, G., M. Sánchez Regaña, and P. Umbert Millet. “Combination of Acitretin and Oral Calcitriol for Treatment of Plaque-Type Psoriasis”. Acta Dermato-Venereologica, vol. 87, no. 5, May 2007, pp. 449-50, doi:10.2340/00015555-0290.