Martin Haspelmath: Understanding Morphology (Understanding Language), 2002. Arnold Publishers, London. ISBN: 0-2040-760265.
Hopper, P.J. and Elizabeth Closs Traugott : Grammaticalization, 1993. Cambridge textbooks in linguistics.
Kompendium: Morfologi 2,
Kjell Magne Yri: Sidaama Morphology,
Ineke Smeets: Mapudungun Morphology of the Verb, Leiden 1989. Doctoral dissertation.
Kjell Magne Yri: Decategorialization of Nouns as Postpositions in Sidaamu Afo and Amharic,