Filioque
James Likoudis.  Ending the Byzantine Greek Schism. New Rochelle, New York: 1992. An apologetic response to polemical attacks. A useful book for its inclusion of important texts and documents; see especially citations and works by Thomas Aquinas, O.P., Demetrios Kydones, Nikos A. Nissiotis, and Alexis Stawrowsky. The select bibliography is excellent. The author demonstrates that the Filioque dispute is only understood as part of a dispute over papal primacy and cannot be dealt with apart from ecclesiology.