Attempts have been made by Soviet scholars to establish a relationship with either Burushaski or the Sino-Tibetan languages, and it frequently forms part of the Dene–Caucasian hypothesis. None of these attempts has been conclusive. Joseph Greenberg proposed a link between Ket and other Yeniseian languages and the Na-Dene language group of North America in his final study of Eurasiatic languages. In February 2008, the linguist Edward Vajda also submitted a paper on the proposed link between Ket with the Na-Dene languages. Now published in 2010, Vajda's paper has been favorably reviewed by several experts on Na-Dene and Yeniseian languages, including Michael Krauss, Jeff Leer, James Kari, and Heinrich Werner, as well as a number of other well-known linguists, including Bernard Comrie, Johanna Nichols, Victor Golla, Michael Fortescue, and Eric Hamp, so that a broad consensus has formed in support of this connection . Some experts on Yeniseian remain extremely skeptical or reject the hypothesis (e.g. Stefan Georg).