SUMIFS Across Multiple WorkSheets

I have a workbook with multiple worksheets and each worksheet will be identical. I have a summary sheet and I would like to do a SUMIFS across all the worksheets if it meets certain criteria.


On the summary sheet in cell C8 I want to sumifs with the follow criteria.

Worksheets: Criteria Range 1 = Column A, Criteria 1 = "Drafting"
Criteria Range 2 = Column B, Criteria 2 = "External"
Sum Range = Column N

I hope that makes sense. Please see attached example file.