Two of the most valuable books I've ever read on the early Church, recommended to me by a now-deceased priest...another "towering intellect," are these.
EUSEBIUS (A.D. c260-399): The History of the Church
and
RICHARD M. HOGAN: Dissent From the Creed Heresies Past and Present
I reread them every once in a while and PARTS because they are so clear and full of factual information.
Eusebius didn't have a bibliography or index, of course. :o)
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One interesting tidbit in Eusebius' book:
There is a copy of a letter written by Abgar the Toparch to Jesus and sent to Him at Jerusalem by the courier Ananias, followed by JESUS' REPLY to the Toparch Abgar also sent by the courier Ananias.
I had to look up "toparchy."
You can google all of the above.
My, isn't the Internet fabulous?
Looks like fascinating but deep reading.