Novgorodsko-Sofiysky Svod
The Novgorodsko-Sofiysky Svod is a tentative name for a hypothetical common source for the Novgorod Fourth Chronicle and the Sofia First Chronicle, according to Russian philologist Aleksey Shakhmatov.
Shakhmatov initially dated it by the year 1448, but later revised his opinion to the 1430s. Some Russian philologists shared his opinion, while others attribute the common source to the 1418 compilation of the 15th century Photius, Metropolitan of Moscow.