Canon 7 of the III Ecumenical council: its history and reception in the context of the issue of the Immutability of the creed - Petr Paskov (Vestnik Pravoslavnogo Svâto-Tihonovskogo Gumanitarnogo Universiteta: Seriâ II. Istoriâ, Istoriâ Russkoj Pravoslavnoj Cerkvi, 2023)