What happened at the council of Nicaea? Was the Trinity made up there? Was the divinity of Jesus declared there for the first time? This video answers these question?
History of the Christian Church (Eerdmans, 1985)
Faith of the Early Fathers, Vol. 1 (Jurgens, 1998)
The Christological Controversy (Norris, 1980)
The Church History (Eusebius)
Dialogus Adversus Luciferianos (St. Jerome)