Empirical work on identifying and studying previously unknown sources is an obligatory type of occupation of a historian of science. A journal of work records and minutes of meetings of the V. M. Bekhterev Brain Institute laboratory of childhood reflexology in 1925-1928. The first examination of this document yielded results: the dates, names, types of work, laboratory research methods and results of were identified and clarified. Some facts of the biography of B. G. Ananiev and other scientists of the Leningrad (St Petersburg) psychological school. The documentary confirmation of personal contacts of B. G. Ananiev and V. M. Bekhterev was found, the content of the laboratory work was concretized, the research topics, measures of staff training, the degree of popularity of the Institute and its Museum in the country and abroad, connections with foreign psychology were clarified.