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(1)
Peter Hajdu, The Samoyed peoples and languages, Szeged 1963
(2)
Peter Hajdu, Finno-UgrianLanguages And Peoples, Great Britain 1975
(3)
Johanna Laakso, Vorlesungsfolien, Universität Wien WS 2011
(4)
http:www.langwhich.com/lexikon/sprachen-und-Völker-der-Erde/enzen