The Museum of the American Indian (a branch of the Smithsonian) located in the old Customs House in lower Manhattan - right across from Battery Park - has a resource room/library which is open whenever the museum is. They have a reasonable amount of data on this subject, though not, unfortunately, the Strong book. Sorry not to have the URL to hand, but they maintain a website which gives such elementary info as how to get there and the times they're open. Any of the search engines will doubtless turn it up. Beverly Martin