“extractus”, inCharlton T. Lewis (1891),An Elementary Latin Dictionary, New York: Harper & Brothers
"extractus", in Charles du Fresne du Cange,Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)