I want to know the answer to the following question:
What writing mentions the Arian accusation that Athanasius was under aged?
All the background I'm provided with is that "Secondly, the Festal Epistles state that the Arians had accused Athanasius, among other charges, of not having yet attained the canonical age (30) and thus could not have been properly ordained as Patriarch of Alexandria in 328.". Is that enough to answer the question?
Answer: yes