You would normally use INDIRECT to construct a cell reference as a string and then get Excel to recognise it as a cell reference.

However, INDIRECT does not work with closed workbooks, so you won't be able to use it in this instance.

One way around this limitation is to download the free add-in morefunc (do a Google search for sites where you can download it from), which will enable you to use the function INDIRECT.EXT, which does work with closed workbooks.

Hope this helps.

Pete