One embodiment provides a method, including: receiving, from a user, a natural language query; generating an ontology subgraph by mapping the natural language query to a domain ontology and filtering the domain ontology based upon entities within the natural language query; producing a knowledge graph from (i) the generated ontology subgraph and (ii) a set of documents related to the natural language query, wherein the producing comprises extracting triples from the set of documents and aggregating the extracted triples to form the knowledge graph; and providing, to the user, a response to the received natural language query, wherein the returning the response comprises querying the produced knowledge graph using the natural language query.