History of Frederick the Second: Emperor of the Romans, From Chronicles and Documents Published Within the Last Ten Years. E-book. Formato PDF T. L. Kington   -  Forgotten Books, 2017  - 

It was not until lately that England furnished any important contributions to the study of the Em peror's life. A few lines in Gibbon, a few pages in Hallam contained all the information respecting it that was readily accessible to an English student.