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 Izhar, Hebron, and Uzziel. And the sons of Merari by their families: Mahli and Mushi. These are the families of the Levites according to their fathers’ houses. Of Gershon was the family of the Libnites, and the family of the Shimeites: these are the families of the Gershonites.