Editors. "Ferdinand of Austria and John Zápolya of Hungary sign Peace of Grosswardein". The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14596, accessed 20 May 2013.]
Rival claimants for the throne of Hungary, Ferdinand of Austria and John Zápolya, sign the Peace of Grosswardein (today Oradea, in Romania). By the terms of this agreement, Zápolya, who is currently childless, agrees to grant the whole of the dominion of Hungary to Ferdinand on his death.