Michelle Cini; Nieves Perez-Solorzano Borragan, eds. (2013). «Glossary». European Union Politics. Oxford University Press. p. 387. ISBN978-0-19-969475-4.
Party Members and Activists. p.85. Published by Routledge. Edited by Emilie van Haute and Anika Gauja. Published 24 April 2015. Retrieved 22 August 2017. Retrieved via Google Books.
‘He Does Not Understand What the Role of an Ambassador Should Be’. 'U.S. Ambassador Ric Grenell managed to shock and offend Berlin’s political class in his first month on the job. Now protocol-loving Germans are wondering—will he learn to change?' POLITICO magazine. Published 25 June 2018. Retrieved 12 July 2018.
