Commentaries and Translations of the Sources of Orthodox Canon Law

The Roman Law Library
https://droitromain.univ-grenoble-alpes.fr/

Canonical Letters of St Basil
Letter 188 (First canonical letter): https://www.newadvent.org/fathers/3202188.htm
Letter 199 (Second canonical letter): https://www.newadvent.org/fathers/3202199.htm
Letter 217 (Third canonical letter): https://www.newadvent.org/fathers/3202217.htm

K. J. von Hefele, A History of the Christian Councils
Vol. 1: https://books.google.at/books?id=hshKAQAAMAAJ
Vol. 2: https://books.google.at/books?id=VMhKAQAAMAAJ
Vol. 3: https://books.google.at/books?id=IB4RAAAAYAAJ
Vol. 4: https://books.google.at/books?id=_b9lAAAAMAAJ
Vol. 5: https://books.google.at/books?id=HEsMAQAAMAAJ

W. Bright, The canons of the first four general councils of Nicaea, Constantinople, Ephesus and Chalcedon: with notes
https://books.google.at/books?id=GD5ZAAAAMAAJ

H. R. Percival, The Seven ecumenical councils of the undivided church : their canons and dogmatic decrees, together with the canons of all the local synods which have received ecumenical acceptance
https://archive.org/details/sevenecumenicalc00perc/

H. J. Schroeder, Disciplinary decrees of the general councils, text, translation, and commentary
https://archive.org/details/DisciplinaryCouncils/