This edition contains for the first time all the correspondence of I.A. Efremova. The code includes 1275 letters: this is correspondence with major Russian and foreign scientists - paleontologists, geologists, literary scholars, orientalists, with famous Soviet and foreign writers, with young people, close people. About two hundred participants in the correspondence are represented. The depth and breadth of the problem will allow readers to see the life and aspirations of thinking people of the 20th century on a large scale.