6. A method for checking related document according to the document relationship determined by the method in claim 1 , comprising: receiving an entry document selected by a user; checking the related document which has relationship with the entry document; and returning a checking result which contains the related document to the user.
7. The method of claim 6 , wherein returning the checking result to the user further comprises returning the one or more search queries associated with the entry document, and the related document associated with the entry document to the user, wherein the related document is indexed by the one or more search queries.