Sergei Taneyev
Bogatyrev utilized primary sources, including Tchaikovsky's initial rough sketches, the full orchestral manuscript of about half of the first movement, and the manuscript and printed score of the 3rd Piano Concerto. The one-movement piano concerto was fully orchestrated by the composer, while the second and fourth movements were later orchestrated by Sergei Taneyev, Tchaikovsky's friend and fellow composer.