Acts 20:7 (RSV) On the first day of the week, when we were gathered together to break bread, Paul talked with them, intending to depart on the morrow; and he prolonged his speech until midnight.
1 Corinthians 10:16-17 The cup of blessing which we bless, is it not a participation in the blood of Christ? The bread which we break, is it not a participation in the body of Christ?  Because there is one bread, we who are many are one body, for we all partake of the one bread.
From Sabbath to Sunday: How the Church Moved Its Holy Day (James P. Guzek, This Rock, February 1999)
Did the Catholic Church “Change the Sabbath”? (Jimmy Akin, National Catholic Register, 11 October 2012)
The Catholic Encyclopedia: “Sunday”
The Catholic Encyclopedia: “Sabbath”
The Catholic Encyclopedia: “Sabbatarianism, Sabbatarians”
On Keeping the Lord’s Day Holy (Dies Domini) (Apostolic Letter of Pope John Paul II: 31 May 1998)
Sunday vs. The Sabbath (Dr. Tim Gray, 12 March 2012; Catholic Answers Live, audio)
Did Jesus alter the commandment about observing the sabbath? (Catholic Answers: “Quick Questions”)
The Sabbath or the Lord’s Day (Catholic News Agency)
How Should We Keep the Sabbath? (Fr. William Saunders, Arlington Catholic Herald, 25 May 1995)
Should We Keep the Sabbath? (James A. Borland, Christian Research Journal, volume 26, number 2, 2003)
Biblical Evidence for Sunday Worship (Dave Armstrong, Biblical Evidence for Catholicism, 12-1-15)
(originally 1-19-08; expanded and bad links removed: 6-28-18)