Exploring place names, persons and topics in the Greco-Roman world.
You can perform a subject keyword search in the entries of the digital New Pauly Encyclopedia and Oxford Classical Dictionary, both of which often provide specific references to these ancient authors. The online IVP Dictionary of New Testament Background is also useful for this purpose. All three of these reference works are also available in print in Buswell's reference collection.
The library provides access to the Digital Loeb Classical Library, an extensive collection of ancient Greek and Latin texts, which enables you to search the series by English keyword together with an author (e.g. Philo, Josephus, Plutarch, Cicero). You can also limit to a particular century (e.g. 1 AD-100 AD).
Another strategy is to find reference to ancient sources in the secondary literature using Google Scholar or Google Books (e.g. women philo)