A simple way is to allow XL to create the reference for you.
And then if you wish, with the exact XL created syntax in front of you, you
can revise and/or create additional ones.
Open both files.
Then go to <Window> <Arrange>,
Select a preferred view, then <OK>.
Navigate each file so that both are displaying the cells you wish to
reference (link).
Select one cell, and enter the equal sign (=),
Then simply click in the "other" cell, and hit <Enter>.
You'll probably have to click on the "other' cell twice, since the first
click will probably just change the focus to the second file, and the second
click will actually select the desired cell.
You will now be able to see the actual referencing formula in the formula
bar.
When you close the "other" file, you'll then see the *full* path to this
file in the formula bar.
This should give you a fine example, which you can revise and/or copy from.
