Ferdinand IV, King of the Romans, who was to have succeeded his
father as Holy Roman Emperor, dies of smallpox at the age of 30.
Citation:
Editors. "Death of Ferdinand IV, King of the Romans".
The Literary Encyclopedia. First published 01 April 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=16385, accessed 24 May 2013.]