I would like to get data from a specified cell in another .xls file. I would like to do this by referencing a cell in the current sheet which has the filename of the external file. For instance:

Say cell A1 has the filename: example1.xls

I would like cell A2 to equal: [example1.xls]c1

I want this to be automated so that if I change the filename, the referenced sheet changes. Is there a good way to do this?