Kalenda, Roman martyrology (Martyrologium Romanum) for 25 December, editio typica of 2001, as mounted by the United States Conference of Catholic Bishops. The immediately previous revision of the Kalenda (sometimes called the Christmas Proclamation) approved by Pope Benedict XV in 1922 read as follows:
In the 5199th year of the creation of the world, from the time when God in the beginning created the heaven and the earth; the 2957th year after the flood; the 2015th year from the birth of Abraham; the 1510th year from Moses, and the going forth of the people of Israel from Egypt; the 1032nd year from the anointing of David King; in the 65th week according to the prophecy of Daniel; in the 194th Olympiad; the 752nd year from the foundation of the City of Rome; the 42nd year of the rule of Octavian Augustus, all the earth being at peace, Jesus Christ, the Eternal God, and the Son of the Eternal Father, desirous to sanctify the world by his most merciful coming, being conceived by the Holy Spirit, nine months after his conception was born in Bethlehem of Juda, made Man of the Virgin Mary. The Nativity of our Lord Jesus Christ according to the Flesh.
Source: The Roman martyrology. . . . An English translation from the fourth edition after the typical edition (1956) approved by Pope Benedict XV (1922), ed. J. B. O’Connell (London: Burns & Oates, 1962), 279.
Image: Bronze coin struck in Antioch, Syria, in 5/4 B.C., at about the time of the birth of Jesus in 6/4 B.C. Obverse: IMP·AVGVST TR·POT (IMPERATOR AUGUSTUS TRIBUNICIA POTESTAS , POTESTATE, etc.); reverse: SC (SENATUS CONSULTUM). Roman provincial coinage, vol. 1, From the death of Caesar to the death of Vitellius (44 B.C. to A.D. 69) (London: British Museum Press; Paris: Bibliothèque Nationale de France, 1992), no. 4247. Color image from http://www.wildwinds.com/coins/ric/augustus/RPC_4247.jpg.
For a history-cum-evolving-text beginning with the "de luxe" Chronograph (ODCC, 3rd ed. rev. (2005), sv Chronographer of AD 354, which cites T. Mommsen in MGH, Auctores Antiquissimi 9.1 (1892), 13–196) written and illustrated for a wealthy Christian named Valentin by the artist Furius Dionysius Philocalus in 354 (which read simply "VIII Kal. Ianuarii, natus Christus in Betleem Iudeae" (Mommsen, 71)), see, among other things, Philippe Beitia, "L'annonce de la naissance du Christ dans le Martyrologe Romain: histoire, évolution et sens théologie," Bulletin de littérature ecclésiastique 105 (2004): 339-352.