The knowledge related to the work of Saints Cyril and Methodius is constantly developing, the Cyrillic alphabet was adapted on the basis of the Greek uncial script, which was well known in the Bulgarian lands at that time, as recalled by the director of the Slavo-Byzantine Research Centre, Vasya Velinova, at a time when we celebrate the 1150th anniversary of the Great Moravia Mission of the two Slavic apostles.