-Francis J. Thomson, Gregory Tsamblak - the Man and the Myths (Ghent: Ghent University, Dept. of Slavonic and East European Studies, 1998): http://books.google.com/books/about/Gregory_Tsamblak_the_Man_and_the_Myths.html?id=nNIkHQAACAAJ
-Muriel Heppell, The Ecclesiastic Career of Gregory Camblak (Verlag, 1979), 134 pp.: http://books.google.com/books/about/The_Ecclesiastic_Career_of_Gregory_Cambl.html?id=1OjDtgAACAAJ
-rival of the schismatic Metropolitan Photius of Kiev (1408-1431)
-Mgr. Julian Pelesz, Geschichte der Union der ruthenischen Kirche Mit Rome (Würzburg-Wien, 1881), vol. 1, 361-365 (PDF pages 373-377):
-In 1418 Gregory I Tsamblak submitted to Pope Martin V of Rome (1417-1431) at the 16th Ecumenical Council (Constance 1414-1418) [Joseph Gill, S.J., The Council of Florence (Cambridge University Press, 2011), 25-27].
-According to Fr. Martin Jugie, Theologia dogmatica christianorum orientalium ab ecclesia catholica dissidentium (Paris: Letouzey et Ané, 19##), vol. 4, 333, Gregory Tsamblak wrote a Catholic exposition of Our Lord's words "Thou art Peter..." (Mt 16:18):
Gregorius Tsamblacus, ex Serbia oriundus, qui metropolitan Kioviensis fuit, eodem fere sensu ac Catholici evangelicum textum Tu es Petrus interpretatur, Petrumque nuncupat fidei petram, regni clavigerum, orbis præfectum4. ...
4. Macarius Bulgakov, op. cit., t. V, p. 457-458.-Francis Dvornik, The Slavs in European History and Civilization (New Brunswick, NJ: Rutgers University Press, 1962) 172: Gregory "composed, among other works, twenty-four homilies and a panegyric on Euthymius [Orthodox Patriarch of Trnovo and Bulgaria] and Cyprian [Orthodox Metropolitan of Kiev and all Rus']. His biography of the Serbian king, Stephen Uroš II, deserves to be mentioned. The biography of St. Romil attributed to him was actually written by a hermit named Gregory."
Note: Stephen II professed papal primacy in his Profession of Faith for Pope John XXII (1316-1334), during the reign of Nicodemus I (1316-1324), according to Fr. Martin Jugie, A.A. Theologia dogmatica Christianorum orientalium ab Ecclesia Catholica dissidentium IV:373.
-Dvornik 174: "Another life of [Stephen] Uroš III was written, as mentioned above, by Gregory Camblak of Bulgaria."
-Dvornik 226-227: Vitold "induced his Orthodox bishops to elect, in 1415, the Bulgarian Gregory Camblak as metropolitan of Kiev. The Metropolitan Photius of Moscow protested, and the Patriarch of Constantinople, who had refused all Vitold's requests for an independent metropolitan, excommunicated Gregory. This plan may have originated in Jagiello's and Vitold's western policy. They hoped that the presence of the new metropolitan of Kiev and of all Russia at the Council of Constance (1415) would provide incontrovertible evidence that there was no reason why the Teutonic Order should be allowed to continue its activity in Prussia: not only had all pagans in those parts been converted, but the Poles and Lithuanians were also bringing back to Rome the Russian schismatics. The whole plan misfired. The learned Bulgarian refused to back their polical plans and turned down the proposals of the council for reunion. After his death (1419), the Muscovite metropolitan continued to exercise his jurisdiction over the Lithuanian Orthodox."
Editor: Dvornik implies that Gregory was Orthodox; this contradicts Jugie and Gill, whose work testifies that Gregory was Catholic after the Council of Constance. In the footnotes to this section of the chapter, Dvornik refers to Albert Maria Ammann, S.J. Abriss der Ostlawischen Kirchengeschichte, Vienna 1950, 73-129; I have to comb this section to find any relevant info that may answer the question of Gregory's ecclesiastical allegiance.
-Oscar Halecki, From Florence to Brest (1439-1596), 2nd. ed., (Archon Books, 1968), 27, 28, 29, 30, 31, 34, 37, 44:
28: Patriarch Joseph II of Constantinople excommunicated Gregory Tsamblak, as did his predecessor the Orthodox Patriarch Euthymius II of Constantinople.
31: "... the spectacular audience of the Metropolitan of Kiev seems not to have been followed by any further negotiations with him, and ... soon after his return from Constance Tsamblak disappeared, maybe retiring to a Moldavian monastery.70 ... 70 This is the hypothesis of [A.I.] Yatsimirsky (see above, note 54 [Grigoriy Tsamblak, Petersburg 1904]); see also Chodyrnicki, 47 note 4."
-Dmytro Blazejowskyj, Hierarchy of the Kyivan Church (861-1990) (Ed. Univ. Cath. Ucr. Clementis Papae, Opera N. 72, Sacrum Ucrainae Millenium, No. 3.), 90-91:
-Roger Aubert, Dictionnaire d'histoire et de géographie ecclésiastiques. Paris: Letouzey et Ané, 2000-2003, vol. 28, cols. 1494-1501: "Shortly before his death (September 1406), Metropolitan Cyprian called his nephew Gregory (cf. 52. CAMBLAC Gregory, supra, XXI, 1486-88) to travel to Kiev with the intent to ensure his succession. But Cyprian died before the arrival of Gregory and the Patriarch of Constantinople appointed a Greek Photius (1408-1431) to replace it. The new Grand Prince of Lithuania, Vitovt, refused to recognize this and he tried to detach the bishoprics of his dominions within the jurisdiction of the Metropolitan of Moscow by electing Gregory as Metropolitan of Kiev with residence in Vilna. The Patriarch of Constantinople excommunicated him, and Gregory, at the request of Vitovt, led a delegation to the Lithuanian-Russian Orthodox Council of Constance (his position in favor of union with Rome is not clear)."
-English Wikipedia (http://en.wikipedia.org/wiki/Gregory_Tsamblak):
-Polish Wikipedia (http://pl.wikipedia.org/wiki/Grzegorz_Camb%C5%82ak):
-Ukrainian Wikipedia (http://uk.wikipedia.org/wiki/%D0%93%D1%80%D0%B8%D0%B3%D0%BE%D1%80%D1%96%D0%B9_%D0%A6%D0%B0%D0%BC%D0%B1%D0%BB%D0%B0%D0%BA):
-Russian Wikipedia (http://ru.wikipedia.org/wiki/%D0%93%D1%80%D0%B8%D0%B3%D0%BE%D1%80%D0%B8%D0%B9_%D0%A6%D0%B0%D0%BC%D0%B1%D0%BB%D0%B0%D0%BA):
-Romanian Wikipedia (http://ro.wikipedia.org/wiki/Grigore_%C8%9Aamblac):
-Popes were Gregory XII (1406-1415; †1417) and Martin V of Rome (1417-1431)
-Greek patriarchs of Constantinople were Euthymius II (1410-1416) and Joseph II (1416-1439), who died a sincere Catholic [AASS 8:I:184F-186E (210-212)]
-Titular Latin Patriarch of Constantinople was Jean de La Rochetaillée (1412-1423; †1437)