Obtain the 2-volume set of Twain-Howells letters, Belknap Press/Harvard, circa 1960, and locate the James-related letters in the index.  Likely your best starting point, other than the UC-Berkeley MT Papers site, which is easily searchable and includes text or summaries of relevant notes and letters.
MZ, KC, MO
-------------- Original message from Mark Dawidziak <[log in to unmask]>: -------------- 


> A friend is working on a paper about Mark Twain and James (that's 
> Henry, not Jesse). He has asked me to forward this question to the 
> Forum: Beyond the standard biographies of both men and the "Turn East, 
> Turn West" book, is there a significant work examining what Twain felt 
> about James and James felt about Twain? He has found an intriguing 1910 
> essay about them -- "Two Frontiersmen" -- but is hoping for something a 
> tad more recent. 
> He knows of the infamous shot Twain took at "The Bostonians" in the 
> 1885 letter to Howells, and he knows about their scattered meetings. Any 
> suggestions?