The method and apparatus of the present invention generates clusters of documents in a collection of linked documents based on co-citation analysis. The frequency linkage is determined for each document in the collection. In other words, the number of times each document is linked to by another document in the collection is determined. Further, a minimum frequency linkage (link frequency threshold) is specified based on a predetermined minimum frequency of document linkage. Additionally, a list of pairs of documents that are linked to by the same document is created so that each of the pairs of documents has a count of the number of times (co-citation frequency) that they are both linked to by another document. Pairs of linked documents are clustered using a suitable co-citation technique.