The article is devoted to the problem of constructing a semantic library of resources on mathematics and mathematical physics based on classical encyclopedias. The mechanism of integration of encyclopedias into the content of the semantic library and the unification of the mathematical encyclopedia edited by academician I.M. Vinogradov and the encyclopedia of mathematical physics edited by academician L.D. Faddeev are investigated. During the integration process, intersections of multiple articles in these encyclopedias are discovered, as well as mutual enrichment of descriptions of their terms. The library’s tools made it possible to form a knowledge graph into which both encyclopedias were integrated. Thanks to the ontological approach, the knowledge graph of the semantic library is saturated with new nodes and links, which in turn leads to the enrichment of the subject areas of the semantic library itself and the subject areas of integrated scientific publications. The library search is accompanied by navigation based on a knowledge graph, which allows you to rely on reliable information from classic encyclopedic sources. The work is addressed to specialists in the field of semantic modeling of scientific subject areas.