You are likely to use a range of source types in your research, and each type of source requires particular information to be included in the corresponding reference.
Selecting the appropriate source type when creating a reference will help the reader to find the exact item you are referring to.
This is especially important for items which are published both online and in print/paper format, as page numbers may be different or information may have been updated online but not in print.
For example, when referencing an online article, you may have to indicate that the source is online, and provide the URL and date accessed. This is the case for Leeds Harvard and Leeds Numeric, but check your referencing style for more details.
If you download or read a PDF from a website, you must reference the actual document type, for example a book chapter, a government report or a leaflet, not the file format (PDF).