How do I “Create a Reference To a Different Workbook” that supports closed workbooks

Question

I want to do something like this: Create a Reference To a Different Workbook (look for this section in the page).
However, the instruction says that the documents must be opened for the INDIRECT function to work.

How can I make it work even if the documents are closed?
Any other solutions / alternatives?
I don't want to open each file and link it manually.
I want to be able to input the filename only, assuming the files are all in the same folder.

Answer 1

There is a UDF version of INDIRECT (INDIRECT.EXT) available from http://xcell05.free.fr/morefunc/english/ that allows access to external workbooks even when they are closed

EDIT

Just checked the page and the download link doesn't work, but the download files can be found here, including the download for MoreFunc version 5.06 which contains the INDIRECT.EXT function