With the significant growth in the number of available electronic documents on the Internet, intranets, and digital libraries, the need for developing effective methods and systems to index and organize E-documents is felt more than ever. In this paper we introduce a new method for automatic text classification for categorizing E-documents by utilizing classification metadata of books, journals and other library holdings, that already exists in online catalogues of libraries. The method is based on identifying all references cited in a given document and, using the classification metadata of these references as catalogued in a physical library, devising an appropriate class for the document itself according to a standard library classification scheme with the help of a weighting mechanism. We have demonstrated the application of the proposed method and assessed its performance by developing a prototype classification system for classifying electronic syllabus documents archived in the Irish National Syllabus Repository according to the well-known Dewey Decimal Classification (DDC) scheme.