The Convert's Catechism of Catholic Doctrine
Written by Peter Geiermann, C. SS. R. with the aim of clearly presenting Catholic doctrine to non-Catholics. This facsimile reprint of the 1930 edition contains the often quoted questions and answers regarding the change of the solemnity of the seventh-day Sabbath to Sunday:
"Q. Why do we observe Sunday instead of Saturday? A. We observe Sunday instead of Saturday because the Catholic Church transferred the Solemnity from Saturday to Sunday." (p. 50).
This work also contains the convert's "Profession of Faith" which states "images of Jesus Christ and of the Mother of God, ever Virgin, as well as all of the saints should be given due honour and veneration" and "I promise and swear true obedience to the Roman Pontiff, successor of St. Peter, Prince of the Apostles, and Vicar of Jesus Christ." (p. 103).