Behringer, Wolfgang (2011). "Core and Periphery: The Holy Roman Empire as a Communication(s) Universe". The Holy Roman Empire, 1495–1806(PDF). Oxford: Oxford University Press. pp. 347–358. ISBN978-0-19-960297-1. Archived(PDF) from the original on 9 October 2022. Retrieved 7 August 2022.
Behringer, Wolfgang (2011). "Core and Periphery: The Holy Roman Empire as a Communication(s) Universe". The Holy Roman Empire, 1495–1806(PDF). Oxford: Oxford University Press. pp. 347–358. ISBN978-0-19-960297-1. Archived(PDF) from the original on 9 October 2022. Retrieved 7 August 2022.
"Das Brandenburger Tor" [The Brandenburg Gate] (in German). Die Stiftung Denkmalschutz Berlin. Archived from the original on 19 July 2011. Retrieved 14 May 2011.
"Das Brandenburger Tor" [The Brandenburg Gate] (in German). Die Stiftung Denkmalschutz Berlin. Archived from the original on 19 July 2011. Retrieved 14 May 2011.