Considering PIE morpheme structure,*kʷetwor- has too many consonants to be a true primitive morpheme. Tentatively, the feminine stem could point to an elemental "four" of the shape**kʷet- or**kʷetu-.
^Fortson, Benjamin W. (2004, 2010),Indo-European Language and Culture: An Introduction, Oxford: Blackwell
^Sihler, Andrew L. (1995),New Comparative Grammar of Greek and Latin, Oxford, New York: Oxford University Press,→ISBN
^Martirosyan, Hrach (2010), “lmaos”, inEtymological Dictionary of the Armenian Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 8), Leiden and Boston: Brill, page547
^Adams, Douglas Q. (2013), “śtwer”, inA Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European;10), Amsterdam, New York: Rodopi,→ISBN,page703
