Main group 1

• Campbell, Lyle, Historical linguistics: an introduction, Edinburgh, Edinburgh Univ. Press, cop. 1998
• Trask, R. L., Historical linguistics, London, Arnold, 1996

Main group 2

• Hock, Hans Henrich, Principles of historical linguistics, 2. rev. and updated ed., Berlin, Mouton de Gruyter, cop. 1991

Main group 3

• Fortson, Benjamin W., Indo-European language and culture: an introduction, Oxford, Blackwell, 2004
• Mallory, J. P., In search of the Indo-Europeans: language, archaeology and myth, London, Thames and Hudson, cop. 1989
• The Indo-European languages: edited by Anna Giacalone Ramat and Paul Ramat, London, Routledge, 1998

Main group 4

• Fortson, Benjamin W., Indo-European language and culture: an introduction, Oxford, Blackwell, 2004
• Watkins, Proto-Indo-European: Comparison and Reconstruction, Part of: The Indo-European languages: edited by Anna Giacalone Ramat and Paul Ramat, London, Routledge, 1998, p. 25–73

Main group 5

• Beekes, Robert S. P., Comparative Indo-European linguistics: an introduction, Philadelphia, Benjamins, cop. 1995
• Bjorvand, Harald; Lindeman, Fredrik Otto, Våre arveord: etymologisk ordbok, Oslo, Novus, 2000
• Indogermanische Grammatik. Bd 1, Heidelberg, Winter, 1986
• LIV: Lexikon der indogermanischen Verben: die Wurzeln und ihre Primärstammbildungen, Wiesbaden, Reichert, 1998
• Meier-Brügger, Michael, Indo-European linguistics, Berlin ;a New York, de Gruyter, 2003
• Pokorny, Julius, Indogermanisches etymologisches Wörterbuch, Bern, Francke, 1959-1969
• Tichy, Eva, A survey of Proto-Indo-European, Bremen, Hempen, 2006
• Trask, R. L., The dictionary of historical and comparative linguistics, Edinburgh, Edinburgh University Press, cop. 2000