1. A computer-implemented method for comparing content overlap between a first electronic document and a second electronic document, comprising: receiving, at a computer, a search request from a user for documents containing one or more keywords; using the computer to access an electronic database and present to the user a first list of one or more documents in the electronic database based on the one or more keywords, the first list of one or more documents including a first hyperlink for the first electronic document; receiving at the computer a request for the first electronic document via the first hyperlink; determining, in response to the request for the first electronic document, a second list of documents in the electronic database that are similar to the first electronic document, the second list of documents including the second electronic document, and the determining comprising: using the computer to parse a text of each of the first and second documents into constituent units; using the computer to compute a digest of each of the first and second documents based on the constituent units; using the computer to compare the computed digests; using the computer to compute a proportion of common contents between the first and second documents and a proportion of distinct contents between the first and second documents based on the comparison; using the computer to determine a date associated with the first document and a date associated with the second document; and using the computer to determine a direction of borrowing based on the determined dates; and using the computer to display to the user the contents of the first electronic document and a hyperlink to the second electronic document and a graphic indicating the direction of borrowing between the first document and the second document, wherein the graphic includes an arrow oriented to point in the borrowing direction showing a computed direction of flow of the information from a donor document to a borrower document, and wherein the graphic comprises a measure of relationship overlap between the first document and at least one of the second document and a selected portion of the second document.