From the introduction: "In this paper it is argued that the analysis of stress placement in Pirahã offers important new evidence on the proper characterization of prosodic organization as well as the notational devices necessary to express this organization. Specifically, I will show that Pirahã stress placement is intractable to either a grid account (Prince 1983) or a binary branching analysis but that an insightful perspective on a variety of stress related phenomena is available if we assume that Pirahã has ternary, obligatory branching feet. Evidence is presented from the assignment of stress in morphologically simple words, lexical compounds, words with extrametrical suffixes, and transmorphemic stress shifts and clash resolution."
Everett, Daniel L.
"Ternarity and obligatory branching in Pirahã,"
Work Papers of the Summer Institute of Linguistics, University of North Dakota Session: Vol. 30, Article 3.
Available at: https://commons.und.edu/sil-work-papers/vol30/iss1/3