Polish Industrial Workers in the Ruhr (Ruhrpolen) since the End of the 19th Century - McCook, Brian (. The @encyclopedia of migration and minorities in Europe. - 1. engl. ed.. - Cambridge [u.a.] : Cambridge Univ. Press, 2011. - XXXIX, 768 S.. - Ill., Kt.. - ISBN 978-0-521-89586-6, 2011)