Wari’ Periphrastic Pronouns (pdf) looks at periphrastic pronominal paradigms in Wari’, arguing for a central role for paradigms in morphological theory. This appeared in the International Journal of American Linguistics.
Wari Intentional State Constructions looks at a particular type of periphrastic construction in Wari’, arguing that this construction presents serious problems for strictly endocentric models of phrase structure, e.g. X-bar theory. n R. Van Valin (ed.), Investigations of the syntax-semantics-pragmatics interface. Amsterdam: John Benjamins.
In addition to work on Wari’ (free download) and other Amazonian languages, my book Why There Are No Clitics, (free download) is my largest essay on morphology (how words are formed). It was reviewed in Language, among other places. I discuss Piraha morphology in some detail in my A Lingua Piraha e a Teoria da Sintaxe.