7. A system for displaying sources of a fact, comprising: one or more processors; memory; and one or more programs stored in the memory, the one or more programs comprising instructions for implementing: a query receiver to receive a user-formulated factual query, the factual query including one or more query terms and information identifying source documents that include one or more query terms of the factual query and one or more of the factual answer terms of the answer; said answer identifier additionally searching a document database distinct from the fact repository to identify documents matching the user formulated factual query; an answer identifier to identify, from a fact repository, an answer to the factual query, the answer including one or more factual answer terms; a source document identifier, for execution after the answer identifier identifies the answer, to access at least one of the source documents in the document database distinct from the fact repository; a snippet generator to generate a snippet for at least one of the source document, the snippet including one or more query terms of the factual query and one or more of the factual answer terms of the answer; and a response generator to generate a response including the snippet, wherein the snippet itself provides factual information that answers the factual query and information identifying at least a subset of the documents of the documents identified from the document database.
9. The system of claim 7 , wherein the response includes a user-selectable link for requesting a list of the source documents, and the query receiver further includes instructions to respond to user selection of the link by sending a list of the source documents.