1. A method of clustering electronic documents of a document corpus, the method comprising: comparing, by a computer, each individual electronic document in the document corpus with each other electronic document in the document corpus, thereby forming document pairs, wherein the electronic documents of the document pairs are compared by: calculating a similarity value with respect to the electronic documents of a document pair, wherein the similarity value is based on a plurality of attributes of the electronic documents in the document corpus, and the plurality of attributes comprises a citation attribute, a text-based attribute and one or more of the following attributes: an author attribute, a publication attribute, an institution attribute, a downloads attribute, and a clustering results attribute; and associating the similarity value with both electronic documents of the document pair; and applying a clustering algorithm to the document corpus using the similarity values to create a plurality of hierarchical clusters.