These are more specialized reference tools but might be good to add to the bibliographies list: Louis J. Budd, _A Listing of and Selections from Newspaper and Magazine Interviews with Samuel L. Clemens, 1874-1910_, published as a special issue of _American Literary Realism_ 10:1 (Winter 1977), entire. Louis J. Budd, "Listing of and Selections from Newspaper and Magazine Interviews with Samuel L. Clemens: A Supplement." _American Literary Realism_ 28:3 (Spring 1996): 63-90. Machlis, Paul. _Union Catalog of Clemens Letters_ (Berkeley: University of California Press, 1986). Machlis, Paul. _Union Catalog of Letters to Clemens_ (Berkeley: University of California Press, 1992). These are also online at Union Catalogs of Clemens Correspondence http://bob.ucsc.edu/library/mtp/index.html Only the letters from Clemens (and family) are included in the online database so far. A combined index and full references for the Addenda and supplements to Tenney's _Mark Twain: A Reference Guide_ that appeared in _American Literary Realism_ (1977-1983) and the _Mark Twain Circular_ (1987-1988) is available at the Mark Twain Forum's web site: http://web.mit.edu/linguistics/www/forum/mtcindex.html This document also includes volume-by-volume indices of later issues of the _Mark Twain Circular_ that can be easily searched online. Jim Zwick [log in to unmask] http://www.accinet.net/~fjzwick/ http://marktwain.miningco.com/