13. The method of claim 1 , further comprising: assigning a score to the authoritative search result so that the authoritative search result is ranked among a number of highest-ranked first search results.
1. A computer-implemented method comprising: maintaining, by a search system, a mapping from keywords to respective authoritative sites, wherein a site is a collection of resources on the Internet, and wherein the mapping identifies, for each keyword, one or more authoritative sites on the Internet for queries having the keyword, and wherein the authoritative sites for a keyword are sites that the search system has determined are authoritative for the keyword; receiving, by the search system, a first search query; obtaining, by the search system, first search results responsive to the first search query; determining, by the search system, after obtaining the first search results, that the search system should obtain a search result from a site that is authoritative for the first search query, and that a first authoritative site is authoritative for the first search query; in response to the determining, performing, by the search system, a second search limited to resources occurring on the first authoritative site, using a second search query different from the first search query, to obtain an authoritative search result, the authoritative search result being a search result that identifies a resource that is responsive to the second search query and that is on the first authoritative site; ranking, by the search system, search results including the authoritative search result and the first search results; and providing, by the search system, the ranked search results including the authoritative search result and one or more of the first search results in response to the first search query.