^Ringe, Donald (2006),From Proto-Indo-European to Proto-Germanic (A Linguistic History of English; 1)[1], Oxford: Oxford University Press,→ISBN,page117
^Derksen, Rick (2015), “nė”, inEtymological Dictionary of the Baltic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series;13), Leiden, Boston: Brill,→ISBN,page331
^De Vaan, Michiel (2008), “nē”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,pages403-4
^De Vaan, Michiel (2008), “nī”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,page408
^Jan de Vries (1977) [1957–1960], “ni”, inAltnordisches etymologisches Wörterbuch [Old Norse Etymological Dictionary] (in German), 3rd edition, Leiden:E[vert] J[an] Brill,→OCLC,page408.
^Kloekhorst, Alwin (2008), “nekku”, inEtymological Dictionary of the Hittite Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 5), Leiden, Boston: Brill,→ISBN,pages601-602
^De Vaan, Michiel (2008), “ne-”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,page403