Abstract: The problem of representation of mathematical subject domains in digital libraries and usefulness of these resources for experts is discussed. The option of representation of mathematical subject domains on the Internet is given. As information model for unit of record article of the thesaurus is chosen. Implementation of the scheme is shown on the example of the partial differential equations. Approach to the organization of information space of the author is offered, using the thesaurus by the addressee. On the basis of descriptions of subject domains of individuals creation of ontology of scientific cross-disciplinary community is supposed what, according to authors, will allow not to lose new result or opening in science, to observe priorities of authors, to build in new knowledge the settled system of classical subject domains.