'Sons of Levi' in the Bible

These are the names of the sons of Levi according to their generations: Gershon, and Kohath, and Merari; and the years of the life of Levi were one hundred thirty-seven years.

then Moses stood in the gate of the camp, and said, "Whoever is on the LORD's side, come to me." All the sons of Levi gathered themselves together to him.

The sons of Levi did according to the word of Moses: and there fell of the people that day about three thousand men.