Real Academia Española. «diagrama». Diccionario de la lengua española (23.ª edición).
wikipedia.org
en.wikipedia.org
Sir William Hamilton 1860 Lectures on Metaphysics and Logic edited by Henry Longueville Mansel and John Veitch, William Blackwood and Sons, Edinburgh and London. W. Stanley Jevons 1880 Elementary Lessons in Logic: Deductive and Inductive. With Copious Questions and Examples, and a Vocabulary of Logical Terms, M. A. MacMillan and Co., London and New York. John Venn 1881 Symbolic Logic, MacMillan and Co., London. Fuentes citadas en en:Euler diagram#History
