Ladewig Petersen, E. “J. S. Kepler: The Exchange of Christendom. The International Entrepot at Dover, 1621-1651. University Press 1976. 191 S. £ 7.50”. Historisk Tidsskrift, bd. 13, januar 1979, https://tidsskrift.dk/historisktidsskrift/article/view/52186.