Peter Kreeft (1989). “Three Philosophies of Life: Ecclesiastes--life as Vanity, Job--life as Suffering, Song of Songs--life as Love”, p.149, Ignatius Press
Catholic Church. Pope (1846-1878 : Pius IX), John R. Sheets, Pope Pius IX (1854). “Ineffabilis Deus: Defining the Dogma of the Immaculate Conception : Apostolic Constitution of Pius IX, Issued December 8, 1854”, p.21