I have a workbook (workbook1) to track hours. In this workbook are multiple worksheets for the different months. Each worksheet will have multiple dates with multiple clients and the hours work for them. The name of workbook1 does not change.

In a separate workbook (workbook2) I am tracking the cost for the project. This workbook has multiple worksheets for the different months.

Based on the workbook2, client name and current month, I want to search workbook1 for the correct worksheet and sum up the hours worked for that client (column to sum do not change)

Thus I have this formula =SUMIF('[workbook1.xlsx]May-2018'!$C$8:$C$60,'[workbook2.xlsx]Summary'!$B$1,'[workbook1.xlsx]May-2018'!$I$8:$I$60)

I want to replace May-2018 in the above formula with information from workbook2 cell that matches the worksheet name in workbook1.

Thank you for your assistance