Summarizing data from multiple sources

I have attached 2 workbooks. In "Small Line 2018" the assemblers will record their daily finishes. As you can see there is a worksheet for each month. The only data that I am currently interested in is the "Daily Completions". They will enter the daily completions in row 8 under the appropriate day of the month. There are 3 assembly workbooks: Small Line 2018.xlsx, Medium Line 2018.xlsx, and Large Line 2018.xlsx. These 3 workbooks will reside in the same folder. I only attached 1 of the 3. The attachment "Daily Productivity.xlsx" is the management workbook that will contain the summary data. The date is displayed in C1. This management summary will expand as our new processes are being developed. all I care about at this time is the 4 pieces of data coming from each of the individual assembly workbooks and populating the management summary. I hope this gives what you need. Again, thank you very much for your help.