The next issue of the series "M. Gorky. Materials and Research" continues to publish unique documents from the APRF, RCCHIDNI, A.M. Gorky Archive and foreign archives. The book "M. Gorky. Unreleased Correspondence..." includes letters from Gorky to V.I. Lenin, I.V. Stalin, L.B. Kamenev, his correspondence with A.A. Bogdanov, V.G. Korolenko, G.E.Z They allow us to present little-known aspects of the writer's literary and social activities, dramatically tense relations with Soviet power, the struggle to save Russian science and culture. The book also includes an unknown article by Gorky from the cycle "Untimely Thoughts" and the beginning of an essay about Stalin.