Editors. "Hapsburgs agree that Archduke Ferdinand will succeed Charles V". The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14816, accessed 20 April 2014.]
The Hapsburgs sign a family compact, which arranges for the Archduke Ferdinand to succeed to the imperial title and the Hapsburg lands on the death of his brother Charles V, while Charles's son Philip will then succeed Ferdinand. However, this agreement was abrogated with Charles V's abdication in 1555, when his possessions were divided between the two younger men, Ferdinand taking on the Empire, while the Spanish dominions went to Philip.