↑ 1.01.1Fortson, Benjamin W. (2004, 2010) Indo-European Language and Culture: An Introduction, Oxford: Blackwell
↑ 2.02.12.2Klein, Jared S., Joseph, Brian D., Fritz, Matthias, editors ((Can we date this quote?)), Handbook of Comparative and Historical Indo-European Linguistics: An International Handbook (Handbücher zur Sprach- und Kommunikationswissenschaft [Handbooks of Linguistics and Communication Science]; 41.2), Berlin, Boston: De Gruyter Mouton, →ISBN, pages 488, 1318