Uppal S, Diggle CP, Carr IM, etal (junio de 2008). «Mutations in 15-hydroxyprostaglandin dehydrogenase cause primary hypertrophic osteoarthropathy». Nat. Genet.40 (6): 789-93. PMID18500342. doi:10.1038/ng.153.
Pallares-Sanmartin, A; Leiro-Fernandez, V; Cebreiro, TL; Botana-Rial, M; Fernandez-Villar, A (julio de 2010). «Validity and reliability of the Schamroth sign for the diagnosis of clubbing». JAMA304 (2): 159-61. PMID20628128. doi:10.1001/jama.2010.935.
Naeije R (marzo de 2003). «Hepatopulmonary syndrome and portopulmonary hypertension». Swiss Med Wkly133 (11–12): 163-9. PMID12715285.
Uppal S, Diggle CP, Carr IM, etal (junio de 2008). «Mutations in 15-hydroxyprostaglandin dehydrogenase cause primary hypertrophic osteoarthropathy». Nat. Genet.40 (6): 789-93. PMID18500342. doi:10.1038/ng.153.
Branwood, AW (marzo de 1949). «Clubbing of the fingers». Edinb Med J56 (3): 105-20. PMID18130731.
McPhee, Stephen (1990). «44. Clubbing». En Walker HK, Hall WD, Hurst JW, ed. Clinical methods: the history, physical, and laboratory examinations (3 edición). Boston: Butterworth-Heinemann. PMID21250207. Consultado el 13 de junio de 2013.
Pallares-Sanmartin, A; Leiro-Fernandez, V; Cebreiro, TL; Botana-Rial, M; Fernandez-Villar, A (julio de 2010). «Validity and reliability of the Schamroth sign for the diagnosis of clubbing». JAMA304 (2): 159-61. PMID20628128. doi:10.1001/jama.2010.935.