command line - Why do I get "package not found" when trying to install jabref with apt-get?

I can find a particular application 'JabRef' at the ubuntu software centre. But whenever I type sudo apt-get install jabref in terminal, it says package not found. What's going wrong here? Do I have to capitalise the exact letters as in the application name or do I need some additional steps to make sure the terminal looks at the correct repository for the particular installer?

Execute sudo apt-get update first and then try installing jabref again.