If you need to add citations (bibliography) in a scientific paper like a dissertation thesis or a scientific paper, you might find the following site useful: www.citethisforme.com.
Even the free version is good enough, but you will need to periodically save your bibliography elsewhere.
One of the strongest features of the tool is the ability to pull data for a book from its ISBN. It does a similar thing with URLs and Scientific Papers.
It supports multiple citation styles.
Also see: https://www.zotero.org/