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The Leonhard Schultze languages were traditionally classified by Laycock and Z'graggen (1975) as part of the Sepik language family.
Foley (2018) classifies the Leonhard Schultze languages separately as an independent language family rather than as part of the Sepik languages (as in previous classifications proposed by others). However, this classification is not accepted by Glottolog, which splits up the Walio and Papi branches and considers them each to be a primary language family.
Vocabulary comparison
The following basic vocabulary words are from Conrad and Dye (1975), as cited in the Trans-New Guinea database.
The words cited constitute translation equivalents, whether they are cognate (e.g. tiᵽo, tipafu for “head”) or not (e.g. aᵽayo, toefahewa for “skin”).
Laycock, D. C. and Z'graggen, John A. 1975. The Sepik-Ramu Phylum. In Wurm, S.A. (ed.), Papuan Languages and the New Guinea Linguistic Scene, New Guinea Area Languages and Language Study 1, 729-763. Australian National University.
Foley, William A. (2018). "The Languages of the Sepik-Ramu Basin and Environs". In Palmer, Bill (ed.). The Languages and Linguistics of the New Guinea Area: A Comprehensive Guide. The World of Linguistics. Vol. 4. Berlin: De Gruyter Mouton. pp. 197–432. ISBN978-3-11-028642-7.