A method for identifying landmark documents in a document database, wherein each document in the database has a primary citation and a normalized document identifier corresponding to the primary citation, comprising the steps of: (a) retrieving documents from a database, the retrieved documents defining an answer set; (b) following step (a), displaying the answer set to the user, the documents of the answer set being sorted in an order other than by frequency of citation; (c) following step (b), and in response to a user request to re-sort the answer set in an order different from that of step (b), re-sorting the documents in the order requested by the user; and (d) following step (c), displaying the re-sorted answer set to the user; characterized in that: each document that includes a citation to a cited document in the database also includes a normalized document identifier keyword for the citation of the cited document; in step (a), the documents retrieved are the most relevant documents on a topic selected by a user from a pre-defined topical hierarchy; in step (c), the user request is to re-sort the documents of the answer set based on frequency of citation, and prior to re-sorting, normalized document identifiers corresponding to the primary citations of the retrieved documents of the answer set are retrieved, a search request is constructed using the retrieved normalized document identifiers as search terms, wherein the search request contains search terms comprising the normalized document identifiers for each document in the answer set, document frequency counts are generated for each search term within the search request for documents in the answer set by counting occurrences of each normalized document identifier keyword corresponding to a search term within the search request in the documents in the answer set, and the documents within the answer set are re-sorted based upon the document frequency counts, the documents having the highest document frequency counts being identified as landmark documents. (a) retrieving documents from a database, the retrieved documents defining an answer set; (b) following step (a), displaying the answer set to the user, the documents of the answer set being sorted in an order other than by frequency of citation; (c) following step (b), and in response to a user request to re-sort the answer set in an order different from that of step (b), re-sorting the documents in the order requested by the user; and (d) following step (c), displaying the re-sorted answer set to the user; each document that includes a citation to a cited document in the database also includes a normalized document identifier keyword for the citation of the cited document; in step (a), the documents retrieved are the most relevant documents on a topic selected by a user from a pre-defined topical hierarchy; in step (c), the user request is to re-sort the documents of the answer set based on frequency of citation, and prior to re-sorting, normalized document identifiers corresponding to the primary citations of the retrieved documents of the answer set are retrieved, a search request is constructed using the retrieved normalized document identifiers as search terms, wherein the search request contains search terms comprising the normalized document identifiers for each document in the answer set, document frequency counts are generated for each search term within the search request for documents in the answer set by counting occurrences of each normalized document identifier keyword corresponding to a search term within the search request in the documents in the answer set, and the documents within the answer set are re-sorted based upon the document frequency counts, the documents having the highest document frequency counts being identified as landmark documents.