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"Member Churches". utrechter-union.org. Utrecht, NL: Utrechter Union der Altkatholischen Kirchen. Archived from the original on 10 April 2016. Retrieved 28 April 2016.
"Old-Catholic Church in Austria". oikoumene.org. Geneva: World Council of Churches. January 1967. Archived from the original on 29 February 2016. Retrieved 29 February 2016.
"Old-Catholic Church of Switzerland". oikoumene.org. Geneva: World Council of Churches. January 1948. Archived from the original on 29 February 2016. Retrieved 29 February 2016.
"Polish Catholic Church in Poland". oikoumene.org. Geneva: World Council of Churches. January 1948. Archived from the original on 29 February 2016. Retrieved 29 February 2016.
One or more of the preceding sentences incorporates text from a publication now in the public domain: Baumgarten, Paul Maria (1911). "Old Catholics". In Herbermann, Charles (ed.). Catholic Encyclopedia. Vol. 11. New York: Robert Appleton Company.
Davis, Derek H. (Autumn 1998). "Editorial: Religious persecution in today's Germany: old habits renewed". Journal of Church and State. 40 (4). Waco, TX: J. M. Dawson Institute of Church-State Studies at Baylor University: 741–756. doi:10.1093/jcs/40.4.741. ISSN0021-969X.
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