Yes you can.
If you have both workbooks open, you can ...
1) In the cell you want the data to appear in, enter the "=" sign and then
navigate to the other workbook and go to the cell you want to reference and
then hit <ENTER>. NOTE - you will notice a flashing dotted line around the
cell that will be referenced.
Once you hit <ENTER>, you will see how Excel names the target cell reference
in the receiving cells formula bar. You can use that syntax to do cell
references as well - without the target workbook being open.
2) You can also <COPY> the target cell into the referencing workbook and do
<PASTE SPECIAL> and then select the 'Paste Link' button. You will get the
same result doing 1 or 2.
Brett
