^Beekes, Robert S. P. (2011),Comparative Indo-European Linguistics: An Introduction, 2nd edition, revised and corrected byMichiel de Vaan, Amsterdam, Philadelphia: John Benjamins Publishing Company,§17.3, page249
↑3.03.1De Vaan, Michiel (2008), “-dam, -dē, -dō, -dum”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,pages160-161
^De Vaan, Michiel (2008), “endo, indu(-), indi-”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,page189
^De Vaan, Michiel (2008), “-de”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,page162