Numbers 3:17-21

And these were the sons of Levi by their names; Gershon, and Kohath, and Merari. And these are the names of the sons of Gershon by their families; Libni, and Shimei. And the sons of Kohath by their families; Amram, and Izehar, Hebron, and Uzziel. And the sons of Merari by their families; Mahli, and Mushi. These are the families of the Levites according to the house of their fathers. Of Gershon was the family of the Libnites, and the family of the Shimites: these are the families of the Gershonites.