1. A method performed by a system comprising one or more computers, the method comprising: determining that a first search query includes a respective text reference to each of one or more predetermined attributes, wherein each attribute is associated with a first entity type; generating a second search query including the first search query and one or more terms that refer to the first entity type; and evaluating search results obtained for the second search query to select one or more names of entities of the first entity type to include in a response to the first search query, wherein each search result identifies a respective search result resource, and wherein evaluating the search results comprises: identifying occurrences of references to entities of the first entity type in the same search result resource as one or more terms from the first search query; and selecting the names of entities based on the identified occurrences.