David Pingree, "From Alexandria to Baghdad to Byzantium. The Transmission of Astrology," IJCT 8 (2001-2002), pp. 3-37.

It is argued in this article that a series of texts preserved in various Greek manuscripts are epitomes of an astrological compendium assembled by Rhetorius at Alexandria in about 620 AD. It is also demonstrated that this compendium was utilized and frequently refashioned by Theophilus of Edessa between 765 and 775 and was made available by Theophilus to his colleague at the 'Abbasid court at Baghdad, Masha'allah. Masha'allah’s works in turn strongly influenced the early development of Arabic astrology, and many of them were translated into Latin and Greek, thereby spreading Rhetorius’s influence. A manuscript of Rhetorius’s compendium was apparently brought to Byzantium by Theophilus’s student, Stephanus, in about 790; from this archetype are descended the several Byzantine epitomes and reworkings of portions of this text; some of these—pseudo-Porphyry, Ep(itome) III, Ep. IIIb, and Ep. IV—passed through the hands of Demophilus in about 1000, while two of the remainder—Ep. IIb and Ber.—were the only ones to preserve the name of Rhetorius as their author.