Another mention of the "Kyiv prince Theodor" comes from a very late source – the Gustynja Chronicle of the 1620s (GL) [PSRL, 1843, vol. 2, p. 231-337; 2003, v. 40], written, presumably, in the Kyiv-Pechersk Lavra, possibly by Zachary Kopystensky in 1623 – 1627 [Ershov A. When and who wrote the Gustynja Chronicle? – Proceedings of the Shevchenko Scientific Society, 1930, v. 100, p. 205 – 211].
In order to better assess the level of competence and reliability of the annals, and also to determine the methods of chronicler’s work with his sources, I fill, as usual, the table of all episodes in the 14th century. [PSRL, 1843, vol. 2, p. 348 – 352; 2003, v. 40, p. 128 – 132] and try to establish the sources used. At the same time, I will look for sources of borrowing in the books already mentioned, and then I’ll see if there are any news of unknown origin.