“septimum”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
septimum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
septimum in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.