Prussia and Sweden form the Alliance of Stockholm for mutual
defence. They agree to provide military aid for one another if
either is attacked by a third party.
Citation:
Editors. "Prusso-Swedish Alliance of Stockholm for mutual defence".
The Literary Encyclopedia. First published 01 April 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=17554, accessed 26 May 2013.]