1. A method for providing information about a main knowledge stream, the method comprising: obtaining reference links representing reference relationships among reference documents in each of a plurality of documents stored in a database; determining one or more basic paths connecting the reference links; calculating probability values of the reference links by overlapping the determined basic paths; determining a first document from among the documents and an input reference link associated with the first document, and performing a Markov chain model using a probability value of the input reference link; and calculating information about a main knowledge stream associated with the first document using the result obtained by performing the Markov chain model.