וְאֵ֨לֶּה פְקוּדֵ֣י הַלֵּוִי֮ לְמִשְׁפְּחֹתָם֒ לְגֵרְשׁ֗וֹן מִשְׁפַּ֙חַת֙ הַגֵּ֣רְשֻׁנִּ֔י לִקְהָ֕ת מִשְׁפַּ֖חַת הַקְּהָתִ֑י לִמְרָרִ֕י מִשְׁפַּ֖חַת הַמְּרָרִֽי׃
And these are they that were numbered of the Levites after their families: of Gershon, the family of the Gershonites; of Kohath, the family of the Kohathites; of Merari, the family of the Merarites.
Read halakhic rulings (Jewish law) on Numbers 26:57: and classical halakhic sources.