The controversial hypotheses in question fall into two categories. Some of them involve the application of standard historical linguistic methodology in ways that raise doubts as to the validity of the hypothesis. A good example of this sort is the Moscow school of Nostraticists, founded by Vladislav Illich-Svitych and including Aharon Dolgopolsky, Sergei Starostin, and Vitaly Shevoroshkin, who have argued for the existence of Nostratic, a language family including the Indo-European, Afro-Asiatic, Altaic, Dravidian, and Kartvelian language families and sometimes other languages. They have established regular phonological correspondences, observed morphological similarities, and reconstructed a proto-language in accordance with the accepted methodology. Nostratic is not generally accepted, in part because critics have doubts about the accuracy of the correspondences and reconstruction.