Riddick, LR, RH Brodkin, and RC Gibbs. 1971. “Palmar and Plantar Keratoderma With Hyperpigmentation and Gynecomastia. Report of a Case Associated With Primary Adenocarcinoma of the Lung”. Acta Dermato-Venereologica 51 (1):69-72. https://doi.org/10.2340/00015555516972.