Application Not Installing via Terminal

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http://askubuntu.com – 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? (HowTos)