When accessing the links below, you may wish to keep in mind the explanation and clear advice given by Fr. John Mowatt, a Russian Catholic priest, on behalf of our Melkite Catholic brothers.
The Western and Eastern Catholic Churches
The Eastern Christian Churches (CNEWA — a Papal Agency for Humanitarian and Pastoral Support)
Apologia: A Catholic Page for Protestants and Eastern Orthodox.
Hans Schwartz, One Lord and One Church: Wishful Thinking and Hard Realities.
Deno Geanakoplos, Prologue: The Two Worlds of Christendom, in: Byzantine East & Latin West: Two Worlds in Middle Ages and Renaissance, Harper Torch Books, New York 1966.
Michael Azkoul, Orthodoxy and the Transcendence of Religion: A Comment.
Catholic Church in Crete: Catholics and Orthodox: Are we so divided?
Panagiotis Boumis, The Rock of Apostle Peter: A Contribution to the Interpretation of Matt. 16: 18.
Dr. Mikliss de Dolega, Zur Spiritualität der Kirchen in Ost und West (Die Orthodoxe Fraternität in Deutschland).
The 1999 Joint Paschal Message on Ecumenism from the Patriarchs of the Eastern Catholic Churches (in French).
On June 8, 1993, the Pontifical Council for Promoting Christian Unity released a new Directory for the Application of Principles and Norms on Ecumenism, which revises and expands guidelines published in 1967 and 1970.
The Orthodox Christian Laity on the unity among the Orthodox Churches.
Orthodox Leaders Closer to Unity by Elaine Ruth Fletcher, Religion News Service (2000).
Ecumentical News International.
A List of Eastern Catholic Churches and a very complete collection of Ecumenical Links [ Pro Oriente, Austria ]