Mnaseas is reckoned to have been a pupil of a scholar who was chief librarian at what library?
Mnaseas Mnaseas of Patrae (Ancient Greek: Μνασέας ὁ Πατρεύς ) or of Patara, whether that in Lycia or perhaps the Patara in Cappadocia was a Greek historian of the late 3rd century BCE, who is reckoned to have been a pupil in Alexandria of Eratosthenes. His "Periegesis" or "Periplus" described Europe, Western Asia and North Africa, but whether in six or eight books cannot now be determined. His "On Oracles" appears to have consisted of a catalogue of oracular responses with commentary. Only fragments of his work survive, some found in fragmentary papyri at Oxyrhynchus, others embedded as scholia or as quotations in other works, often selected, apparently, because of the unusual interpretations they offer.
Tacitus Publius (or Gaius) Cornelius Tacitus ( ; ] ;  56 AD –  120 AD ) was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the "Annals" and the "Histories"—examine the reigns of the Roman emperors Tiberius, Claudius, Nero, and those who reigned in the Year of the Four Emperors (69 AD). These two works span the history of the Roman Empire from the death of Augustus, in 14 AD, to the years of the First Jewish–Roman War, in 70 AD. There are substantial lacunae in the surviving texts, including a gap in the "Annals" that is four books long.