Inserting contents of a cell into a formula

I hope this is a simple question:

I have 2 excell files. File A contains information per person (> 100 in total) in each seperate sheet. Each sheet is called by the name of the related person.
In File B I would like to import information from file A using a VLookup. In this formula, the table array includes the name of the person as the sheet name. As I want to drag the formula to copy it to different cells, I have to insert the name of the person into the formula from another cell.

Can this be done?

Additional info:

This is the formula
=VLOOKUP($C5,'[jan - aug all personel.xls]Document 122'!$B:$J,9,FALSE)

I would like to replace the bold part by the contents of a cell.