INDIRECT( ) can only get data from files which are open, although
others have referred to Harlan Grove's method of "pulling" data from a
closed file in recent postings - suggest you search for INDIRECT in the
archives. If your sheet names have spaces in them, you will have to
wrap apostrophes around the filename and sheetname as follows:

'c:\path1!sheet1'!A1

Hope this helps.

Pete