Doing a research paper on cleopatra and having a hard time finding any good primary sources
I honestly just use LibGen and archive.org for academic sources. Nice, classic reputable print works that you can just digitally download.
You might like Perseus Tufts as it has both Greek and Latin originals and English translations of Graeco-Roman primary sources.
Lacus Curtius is also very good: http://penelope.uchicago.edu/Thayer/e/roman/home.html