Second Letter of Cyril to Nestorius - Tanner translation. Approved by the Council of Ephesus in 431 as being in conformity with Nicaea. www.dailycatholic.org/history/3ecumen1.htm#Second letter of Cyril to Nestorius
The Epistle of Cyril to Nestorius - Sanborn-Percival translation. With notes. From the Nicene and Post-Nicene Fathers of the Christian Church, second series, vol. 14. www.ccel.org/fathers2/NPNF2-14/Npnf2-14-67.htm
