Numbers 3:21-23 NIV

21 To Gershon1 belonged the clans of the Libnites and Shimeites;2 these were the Gershonite clans.

References for Numbers 3:21

22 The number of all the males a month old or more who were counted was 7,500.
23 The Gershonite clans were to camp on the west, behind the tabernacle.3

References for Numbers 3:23