The documentation consists of a 12-page vocabulary by James Owen Dorsey, three months of fieldwork by Leo J. Frachtenberg in 1911 with a non-English-speaking native speaker and her Alsean husband (who spoke it as a second language), audio recordings of vocabulary by Morris Swadesh in 1953. Frachtenberg (1914, 1922) and Hymes (1966) are publications based on their material.
Dorsey, James Owen. (1884). [Siuslaw vocabulary, with sketch map showing villages, and incomplete key giving village names October 27, 1884]. Smithsonian Institution National Anthropological Archives.