https://www.antiquumdocumentum.co.uk/
Antiquum Documentum | Ornamented Chant and Polyphony
We are an Oxford-based early music vocal group specialising in ornamented chant and polyphony.
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https://www.vatican.va/content/john-paul-ii/la/apost_letters/1996/documents/hf_jp-ii_apl_19961002_antiquum-sane.html
Antiquum sane - Littera apostolica
Sacra paroecialis aedes Visitationis Beatae Mariae Virgins, intra archidioecesis Cracoviensis fines sita, in catalogum Basilicarum Minorum refertur
antiquumsanelitteraapostolica