Editors. "Gustavus II of Sweden encourages James I to join the Thirty Years War". The Literary Encyclopedia. First published 01 February 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=15922, accessed 07 March 2014.]
Gustavus II of Sweden calls upon James I of England to intervene in the Thirty Years War to aid the Protestant cause.