Excel Invoice data retrieval Code/macro in VBA

Hello again Excel Hive Mind!

Still hoping someone can help me with this.

I am looking for the simplest way in VBA to retrieve data from different specific cells in multiple closed workbooks (invoices) and put the data into another workbook for analysis purposes. Once that is done I then need to add code to an existing macro in the invoice (which already saves, closes, prints and then opens a new invoice) so when the macro runs it adds the relevant data to the new workbook. Thanks in advance.

Mark