Charles Ellicott Commentary Judges 1:11

"And from thence he went against the inhabitants of Debir. (Now the name of Debir beforetime was Kiriath-sepher.)" — Judges 1:11 (ASV)

Debir: See Joshua 15:15; Joshua 15:49. In Joshua 10:38-39, its conquest is assigned to Joshua. The name means “the oracle.” It afterwards became a Levitic town. There seem to have been two other Debirs (Joshua 15:7; Joshua 13:26). This one is identified by Dr. Rosen with Dewirban, near the spring Ain Nunkûr south-west of Hebron.

Kirjath-sepher: The name is curious and interesting. It means “the city of the book,” and is rendered in the Septuagint as “city of letters.” It was also called Kirjath-sannah (Joshua 15:49), which, according to Bochart, means “city of learning.” Perhaps, therefore, we may consider that it was a famous centre of Canaanite culture and worship. All further attempts to explain its three names must be purely conjectural. We may compare it with the name of the Egyptian Byblos (Ewald). The Septuagint here falls into mere confusion.