Charles Joseph Hefele, A History of the Councils of the Church: from the Original Documents, to the close of the Second Council of Nicaea A.D. 787 (Wipf and Stock Publishers, 2007) p331.
Charles Joseph Hefele, A History of the Councils of the Church (Wipf and Stock Publishers, 2007) [1].
Eduard Verhoef, Philippi: How Christianity Began in Europe: The Epistle to the Philippians, p 86 (Bloomsbury Publishing, 2013) (online version)
Letters 1–50 (The Fathers of the Church, Volume 76) p8.