From the introduction, "Several recent papers have presented data on switch-reference (subject-change markers) in certain of the Yuman languages. The first article dealing with the subject in general is Jacobsen's "Switch-Reference in Hokan-Coahuiltecan", in which he reports the feature as present in Washo and Kashaya (Southwestern Pomo) but absent in certain other Hokan languages. Winter states that "switch-reference signaled by -m must be reconstructed for Proto-Yuman." As for Proto-Hokan, he believes that we must admit to the possibility that an independent development of switch-reference occurred in various member languages. He considers the likelihood "utterly remote" that a Proto-Hokan switch-reference device might be posited and effectively reconstructed.
"This paper presents the Seri system of subject-change (SC) markers, thereby providing evidence of switch-reference devices from still another Hokan language."
Moser, Mary B.
"Switch-reference in Seri,"
Work Papers of the Summer Institute of Linguistics, University of North Dakota Session: Vol. 20, Article 2.
Available at: https://commons.und.edu/sil-work-papers/vol20/iss1/2