the standardization of the language was due in the first place to the need of the central government for regular procedures by which to conduct its business, to keep its records, and to communicate with the citizens of the land.

여기서 by which to는 어떻게 쓰인건가요..

which가 관계대명사로 쓰인것 같은데.. by랑 to 가 같이 나와서 잘 모르겠네요