The collection is complemented by general reference works (dictionaries, encyclopaedia, etc.) located in the Reading Room, and by the specialised bibliographies and reference works found in the Manuscripts, Fine Arts and Music rooms.

The Biblioteca Nacional de España has gradually incorporated into its assets an extensive collection of bibliographies and catalogues, with Spanish and foreign assets, mostly located in its Bibliographic Information Service.

Throughout the 19th century, the bibliographies collection received many Spanish works together with a few foreign assets. This was the result the purchase of certain works, donations (from private individuals and institutions) or the entry of private libraries such as those belonging to Agustín Durán, Marquis of la Romana or Pascual de Gayangos, amongst others, which contain important bibliographic works from outside Spain.

Over the 20th century, the number of assets increased until the provisions of the Copyright Library Act allowed a complete collection of Spanish works to be formed. In parallel, the purchasing policy of the Biblioteca Nacional has placed particular emphasis on purchasing foreign reference works, considerably increasing the number of these assets as of 1978, the year in which the majority of the Biblioteca Nacional bibliographies were brought together to form the Bibliography Section, which was to become the current Bibliographic Information Service in 1986.

The Bibliographic Information Service includes books, pamphlets and bibliographic-type periodical publications, making them available to users since 1978, with free access and systemically ordered to facilitate search by subject. Moreover, it has a valuable collection of bibliographies and library catalogues on microfilm.

This collection is complemented by general reference works (dictionaries, encyclopaedia, collections of the classics and introductions to a wide range of topics) located in the reading rooms, with free access and with the bibliographies and specialist reference works situated in the Manuscripts and Reserve Prints (Sala Cervantes), Fine Arts (Sala Goya) and Music (Sala Barbieri) rooms.