STM Library uses the Dewey Decimal Classification System (DDC) to arrange most of its materials on shelf according to subject. This arrangement uses letters and numbers to create a call number, which tells you exactly where a specific item can be found on the shelves in the Library, like an “address”. The call number is usually printed on a label affixed to the spine of the book or item. Click on the drop-down menu, or the links below, to find out more: