 Also included in the collection are choreographic notation documenting dances from various operas by both Petipa and Ivanov, respectively.The "Sergeyev Collection" is named after Nicholas Sergeyev, "" of the St. Petersburg Imperial Theatres from 1903 to 1918, who brought the collection out of Russia after the Russian Revolution of 1917.Today, the "Sergeyev Collection" is housed in the Harvard Theatre Collection at Houghton Library, where it has been since 1969.