[1] Emerson, R. W. Business Law. Barron's Educational Series, New York: 2009, p. 756. ISBN 978-0-7641-4240-6 .
[2] Cihon, P. - Castagnera, J. Employment and Labor Law. Cengage Learning, South-Western College/West: 2013, p. 800. ISBN 978-1-1335-8660-9 .
[3] Texts of basic documents (EU Treaty, Treaty on functioning of the EU, Accession Treaty)