1. A method for candidate answer generation in a question answering system, comprising: receiving at least one document responsive to a search of an information source, the search being implemented based on a query formulated from a natural language query; receiving provenance information for the at least one document; searching a semi-structured source of information based on the provenance information; retrieving a substructure corresponding to the at least one document from the semi-structured source of information, the substructure corresponding to structured text; and returning the substructure as a candidate answer to the natural language query; wherein the substructure is anchor text of the document, and wherein the retrieving the substructure includes identifying the document from a database look up table that stores document identifiers and corresponding lists of anchor text, the method further comprising identifying anchor texts in the list that match the anchor texts in the document and selecting as candidate answers all of the anchor texts in the list that are present in the document.