How to: Create external references in a formula.
Solution:
Open the workbook that should contain the formula and the workbooks that are to be referenced in the formula. Type the formula. To include an external reference, switch to the referenced workbook and select the cell(s) or name to be included.
1) Open all the workbooks that are to be referenced in the formula.
2) Open the workbook that should contain the formula.
NOTE: If the workbook is already open, select the 'Window' menu and select the name of the workbook to switch to it.
3) Select the desired worksheet in the workbook.
4) Select the cell that should hold the formula.
5) Type = (an equal sign) to start typing the formula.
6) When an external reference is to be entered, do the following:
a) Select the 'Window' menu and select the name of the workbook to be referenced.
b) Select the cell, range, or name to be included in the formula.
c) Select the 'Window' menu and select the name of the original workbook to switch back to the original workbook.
d) Repeat steps 6)a) through 6)c) for each external reference to be included in the formula.
7) Continue type the formula.
8) Press ENTER when the formula is complete.
NOTE: If the name of a workbook file to which the formula refers is changed or moved, Excel will not be able to update the linked formula. To re-establish links, select the 'Edit' menu and select 'Links...', click 'Change Source...', and specify the new name or location for the file.
