Piotr Wróbel, Rebuilding Democracy in Poland, 1989-2004, in M. B. B. Biskupski; James S. Pula; Piotr J. Wrobel (25 Maio 2010). The Origins of Modern Polish Democracy. [S.l.]: Ohio University Press. pp. 273–275. ISBN978-0-8214-1892-5. Consultado em 4 Jun 2011