L. G. Yi, B. A. Tran, R. H. Flowers, K. E. Greer, and D. J. Guffey, “Treatment of Pityriasis Rubra Pilaris with Daily Low-Dose Methotrexate: A Retrospective Cohort Study”, J of Skin, vol. 5, no. 4, pp. 353–358, Jul. 2021.