BLL Linked Open Data Edition


The Bibliography of Linguistic Literature (BLL) is one of the most comprehensive linguistic bibliographies worldwide. It covers general linguistics with all its neighbouring disciplines and subdomains as well as English, German and Romance linguistics. The BLL dates back as far as 1971 and lists circa 500,000 bibliographic references. Furthermore, the BLL provides a hierarchically categorised thesaurus of domain-specific index terms in German and English. The BLL Thesaurus comprises more than 9,000 subject terms.

The BLL and the BLL Thesaurus have been published and developed by the University Library Johann Christian Senckenberg (University Library Frankfurt). Since 2013, the BLL Thesaurus has also been applied in the context of the Lin|gu|is|tik portal: It provides the thematic classification as well as the standardised vocabulary used for classifying and indexing. Recently, a new application scenario has emerged in the process of connecting the Lin|gu|is|tik portal and the Linguistic Linked Open Data (LLOD) cloud. A Linked Open Data (LOD) edition of the BLL enabled the linking to terminology repositories within the cloud and thus facilitated the connection between the Lin|gu|is|tik portal and LLOD.

The development of the BLL LOD Edition as well as the integration of the LLOD resources in the Lin|gu|is|tik portal is a collaborative project of the University Library and the Applied Computational Linguistics (ACoLi) lab at the Goethe University Frankfurt. The project is supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation).


The BLL LOD Edition has a modular structure. It comprises several components:

  • BLL-Thesaurus represents the original thesaurus in SKOS format, converted in a fully automated manner. The hierarchical structure is expressed by means of skos:broader.
  • BLL-Ontology is based on the the BLL-Thesaurus: The SKOS representation was manually revised, reassessed and remodelled. The hierarchical relations are expressed by means of rdfs:subClassOf.
  • BLL-Index links the BLL bibliographic entries with the corresponding index terms. The relationship to the respective subject term is expressed by means of foaf:topic. BLL-Index includes only freely available bibliographic records (in this case, a Moving Wall of 10 years applies).
  • OLIA-BLL-Link represents an ontology that implements subClassOf relationships between the BLL-Ontology and the OLiA Reference Model.
  • BLL-Language-Link comprises links between the BLL-Ontology and language identifiers provided by Lexvo and Glottolog. The links are expressed on the instance level by means of owl:sameAs, lvont:nearlySameAs, bll:overlaps, bll:hasPart, bll:partOf.
  • BLL-Phoible-Link comprises links between the BLL-Ontology and PHOIBLE concepts designating phonological features.

Versions and updates

About 10,000 citations are added to the bibliography annually. Since the BLL Thesaurus reflects the ongoing development in the field of linguistics, it also evolves over time. This happens mainly by addition of new subject terms, but occasional deletions are not completely ruled out. The LOD edition of the thesaurus, on the other hand, is strictly downward compatible so that existing concepts are never deleted but only marked as deprecated.

There are different update routines for the different components of the BLL LOD Edition:

The BLL-Thesaurus and the BLL-Index are updated on monthly basis. The links and the data dumps (see table below) always provide the latest versions.

The BLL-Ontology is being continuously expanded. The link and the data dump in the table below lead to the latest version. The initial version (2016) comprised mainly subject terms from the thesaurus branches Syntax, Morphology, Lexicology and Phonology. So far, the ontology has been updated two times. In the first update (2020), numerous concepts from the thesaurus branches Indo-European languages and Non-Indo-European languages were integrated in the ontology. The current update (2023) introduces integration of concepts used for indexing in the Lin|gu|is|tik portal. Normally, changes in the existing structure are documented by means of owl:versionInfo. For archiving purposes, we still provide copies of the older versions (

The OLIA-BLL-Link, the BLL-Language-Link, and the BLL-Phoible-Link are updated only if necessary.


The BLL LOD Edition is released under a Creative Commons Attribution licence CC-BY.


Automatically converted SKOS version of the BLL Thesaurus


Manually created OWL model of the BLL-Thesaurus


Mapping of BLL subject terms to BLL bibliographic records


Manually created linking between the BLL-Ontology and OLiA Reference Model


Manually created linking between the BLL-Ontology and both Lexvo and Glottolog


Manually created links between the BLL-Ontology and the PHOIBLE concepts designating phonological features

Via content negotiation, we offer different file formats according to the specification in the HTTP header. For the BLL-Ontology, BLL-Thesaurus, BLL-Index and BLL-Language-Link following mime types are supported: text/turtle, application/n-triples, application/rdf+xml. Additionally, static data dumps are available.