Performing Sumifs on a closed WorkBook

I want to create a Function routine in WorkBook1 that performs the Sumifs calculation on a closed WorkBook2. Does anyone kn开发者_运维百科ow of any simple code?

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SUMIF function will not work with closed workbooks.

A workaround is to use a worksheet with direct references to each significant cell in the closed workbooks and do your SUMIF on this worksheet.