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2 free books about sign language, free to read online. Chapter 1 of any book is free, no account needed.
Sign Language Among North American Indians Compared With That Among Other Peoples And Deaf-Mutes First Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1879-1880, Government Printing Office, Washington, 1881, pages 263-552
Garrick Mallery
Sign talk: a universal signal code, without apparatus, for use in the Army, the Navy, camping, hunting, and daily life
Ernest Thompson Seton
