Иоанн Зонара, Феодор Бальзамон, Матфей Властарь и другие:

Fourth Council of Constantinople (Eastern Orthodox)
The Council of 879-880
...Though this council has been hailed by some Orthodox Christians as the "Eighth Ecumenical Council" it has not been universally accepted as such, though it is held in high esteem at least as a local council and is referred to as the First-and-Second Council by Byzantine canonists John Zonaras, Theodore Balsamon, Matthew Blastaris and others.
(Achim Nkosi Maseko. Church Schism & Corruption)
http://www.reference.com/browse/constantinople,+fourth+council+of