Editors. "Francis I signs an alliance with John Zápolya of Hungary". The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14468, accessed 19 April 2014.]
King Francis I of France signs an alliance with John Zápolya of Hungary, which unites the two forces against the mutual Hapsburg threat of Ferdinand of Bohemia, who is a rival claimant for Zapolya's throne.