[reference] How do I make a relative reference to another workbook in Excel?

The only solutions that I've seen to organize the external files into sub-folders has required the use of VBA to resolve a full path to the external file in the formulas. Here is a link to a site with several examples others have used:

http://www.teachexcel.com/excel-help/excel-how-to.php?i=415651

Alternatively, if you can place all of the files in the same folder instead of dividing them into sub-folders, then Excel will resolve the external references without requiring the use of VBA even if you move the files to a network location. Your formulas then become simply ='[ComponentsC.xlsx]Sheet1'!A1 with no folder names to traverse.