1. A recording medium readable by a computer, the recording medium storing a document management program executable by the computer to perform a function for classifying and managing documents, the function comprising: storing classification scheme information representing a predetermined classification scheme; using, as a reference source database, at least one external database that classifies and manages documents, and acquiring, as reference source classification scheme information, information relating to the classification scheme of the documents at the reference source database; determining, on the basis of the acquired reference source classification scheme information, a way to change the stored classification scheme information; and changing the stored classification scheme information on the basis of the determined way of the changes.