Room Ref Text of treaties never entered into force. This is Vol.2 of a 7 volume P.D. set entitled Indian Affairs, Laws, and Treaties. The other volumes do not include treaties so you can save some time by paging for this if you don't need the other materials. 6-7 are P.D. I1.107 and cover up to 1970. If the U.S. is possibly a party to the treaty, try sources listed above.
Main indices are by party and keyword.
There's actually a wealth of information on treaties here at the library including books that discuss them, indexes to them, and full text. Carnegie Endowment for International Peace. Division of International Law. This is a large set. Latest on UN Ref.