Natick Dictionary

James Hammond Turnbull (1821-1897) was a philologist (which means he studied languages). He didn't work directly with Algonkian-speaking Indians, but was fortunate to have the chance to "deciper rough phonetic accounts" passed down from the 1600's and 1700's (source). (Undoubtedly John Eliot's Natick Bible was used.)

If you're not already familiar with any Algonkian languages, but want to learn one or more, the Natick Dictionary might be the best place to start becasuse words are translated both from Natick to English, and also from English to Natick. Turnbull is given credit for being the first white scholar to understand how highly systematic the Algonkian languages were [are].

Although recently reprinted by the University of Nebraska Press, the Natick Dictionary was originally printed by the United States Government Printing office about six years after Turnbull's death and that edition can now be found online thanks to Google.