“usquam”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
“usquam”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
usquam in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette
De Vaan, Michiel (2008), “usquam”, in Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill, →ISBN, page 646
Ernout, Alfred; Meillet, Antoine (1985), “usquam”, in Dictionnaire étymologique de la langue latine: histoire des mots (in French), with additions and corrections of Jacques André, 4th edition, Paris: Klincksieck, published 2001, page 1336