The fall line was an important early source of water power.

Can these early sources be identified, and if so, how?

Earlier sources for the song's melody have not been found.

Other early sources, however, describe it as a green stone.

This piece of information and similar, can also be found in earlier literary sources from where it is probably taken.

The date of the battle is reported differently in the early sources.

However, the early sources indicate that in reality it was mainly political.

The chronicle contains a large number of facts not found in earlier sources.

Thus the location of Joseon as in these earlier sources is not clear.

To begin with, he gives four answers that have been given in earlier sources and manuscripts.