Reference for Exodus 36:27

וּֽלְיַרְכְּתֵ֥י הַמִּשְׁכָּ֖ן יָ֑מָּה עָשָׂ֖ה שִׁשָּׁ֥ה קְרָשִֽׁים׃

And for the hinder part of the tabernacle westward he made six boards.

BDB