From the introduction, "In this paper, we shall first summarize the findings of several scholars who have contributed to recent literature describing the history of tone in the Tai languages; we shall then focus on one problem that, to my knowledge, has not yet received sufficient attention: namely the reasons for widely divergent patterns of register development, in view of evidence for consonant-pitch correlation which might lead us to expect greater uniformity within the language family."
"The development of Tai register patterns,"
Work Papers of the Summer Institute of Linguistics, University of North Dakota Session: Vol. 14, Article 5.
Available at: https://commons.und.edu/sil-work-papers/vol14/iss1/5