Catechism of the Catholic Church §1137 — excerpt
The book of Revelation of St. John, read in the Church's liturgy, first reveals to us, "A throne stood in heaven, with one seated on the throne": "the Lord God."
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: Liturgy of St. John Chrysostom, Anaphora