The Russian State Library was founded in 1862 and comprises a unique collection of Russian and foreign documents in nearly 250 languages. Stocking nearly 45 million library units, the State Library is one of the largest in the world. Between 1922 and 1991 at least one copy of every book published in the USSR was deposited with the library; and similar practice holds currently, with the library being designated by law as a place to hold a "mandatory" copy of every publication issued in Russia.