The Russian State Library and the National Library of Russia launched a joint project aimed at publishing the library data of the libraries that are the members of the National Digital Library, in accordance with the principles of Linked Open Data. This project will provide access to bibliographic information stored in several of the largest libraries of Russia, in the form suitable for automatic processing. The data set consists of tens of millions of records. A number of urgent problems have to be solved during the process of semantic integration, such as the development of the domain ontology, the conversion of library data from various MARC-formats to RDF, publication of data and provision of SPARQL access points to the data. Public access to one of the world's largest array of bibliographic information with the possibility to detect semantically related data will contribute to the development of culture as a whole and also of specific areas of publishing industry.