1. A method for searching a corpus of documents, comprising: defining a knowledge domain; identifying a set of reference documents in the corpus pertinent to the domain; inputting a first query; searching the corpus using the set of reference documents to find one or more of the documents in the corpus that contain information in the domain relevant to the first query; and adding at least one of the found documents to the set of reference documents for use in searching the corpus for information in the domain relevant to a second, subsequent query, which is substantially different from the first query, wherein searching the corpus comprises searching the corpus to find the documents that contain the information relevant to the query and ranking the found documents by comparing them to the set of reference documents, and wherein ranking the found documents comprises assessing links between the found documents and the reference documents.