Marju Lauristin; Sten Hansson. Estonia. Miloš Gregor; Otto Eibl (编). Thirty Years of Political Campaigning in Central and Eastern Europe. Springer International. 2019: 27 [2023-03-17]. ISBN 978-3-03-027693-5. (原始内容存档于2023-03-15).
Marju Lauristin; Sten Hansson. Estonia. Miloš Gregor; Otto Eibl (编). Thirty Years of Political Campaigning in Central and Eastern Europe. Springer International. 2019: 27 [2023-03-17]. ISBN 978-3-03-027693-5. (原始内容存档于2023-03-15).