^ De Vaan, Michiel (2008) Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7)[2], Leiden, Boston: Brill, →ISBN
^ Adams, Douglas Q. (2013) “eṅk-”, in A Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European; 10), Amsterdam, New York: Rodopi, →ISBN, pages 81-82