^Peter Christian Jacobsen and Peter Orth (2020 June 14) “Materialien zu einem Lexikon der irregulären lateinischen Prosodie”, inwww.mgh.de[1] (in German)
"diabolus", in Charles du Fresne du Cange’sGlossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)