Reference for Joshua 21:40

כָּל־הֶ֨עָרִ֜ים לִבְנֵ֤י מְרָרִי֙ לְמִשְׁפְּחֹתָ֔ם הַנּוֹתָרִ֖ים מִמִּשְׁפְּח֣וֹת הַלְוִיִּ֑ם וַיְהִי֙ גּוֹרָלָ֔ם עָרִ֖ים שְׁתֵּ֥ים עֶשְׂרֵֽה׃

All these were the cities of the children of Merari according to their families, even the rest of the families of the Levites; and their lot was twelve cities.

BDB