^Mayrhofer, Manfred (1992),Etymologisches Wörterbuch des Altindoarischen [Etymological Dictionary of Old Indo-Aryan][1] (in German), volume 1, Heidelberg: Carl Winter Universitätsverlag, page709
^Fortson, Benjamin W. (2004, 2010),Indo-European Language and Culture: An Introduction, Oxford: Blackwell, page112
^Ringe, Donald (2006),From Proto-Indo-European to Proto-Germanic (A Linguistic History of English; 1)[2], Oxford: Oxford University Press,→ISBN,page87
^Adams, Douglas Q. (2013), “śak”, inA Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European;10), Amsterdam, New York: Rodopi,→ISBN,pages674-675