@book {Lehmann1993, title = {Theoretical bases of Indo-European linguistics}, year = {1993}, note = {

Includes bibliographical references (p. 298-315) and index

}, pages = {XI, 324}, publisher = {Routledge}, organization = {Routledge}, edition = {1}, address = {London ; New York}, keywords = {Indo-European languages {\textendash} Research {\textendash} History, Proto-Indo-European language}, author = {Lehmann, W. P.} } @inbook {Weinreich1968, title = {Empirical Foundation for a Theory of Language Change}, booktitle = {Directions for historical linguistics: A symposium}, year = {1968}, pages = {95{\textendash}188}, publisher = {Univ. of Texas Press}, organization = {Univ. of Texas Press}, address = {Austin, {TX}}, keywords = {Historical linguistics, language change, езикова промяна, историческа лингвистика}, author = {Weinreich, Uriel and Labov, William and Herzog, Marvin I.}, editor = {Lehmann, W. P. and Malkeil, Yakov} } @book {Lehmann1952, title = {Proto-Indo-European Phonology}, year = {1952}, publisher = {University of Texas Press}, organization = {University of Texas Press}, address = {Austin, TX}, url = {http://www.utexas.edu/cola/centers/lrc/books/piep00.html}, author = {Lehmann, W. P.} }