These sources consist of two letters from Warren E. Buffett to his partners in Buffett Partnership, Ltd., detailing the fund's operations and financial performance in the early 1960s. The first letter, dated July 1961, announces the shift to a semi-annual correspondence and outlines extensive proposed changes to merge all existing partnerships into a single entity with a revised profit-sharing structure. The second letter, written in January 1962, reviews the partnership's impressive 1961 performance, showcasing substantial gains well above the Dow-Jones Industrial Average. This later communication also thoroughly explains the partnership's investment strategy—categorized as "generals," "work-outs," and "control" situations—and justifies using the Dow as a benchmark for performance while discussing the impact of increasing fund size.