Accessing the values of one calculated field in another such field from the Pivot Table menu doesn't seem possible.
Here are two facts that were encouraging, but I suspect are dead ends:
- Access columns from the origin sheet of your pivot table via their header values;
- There is a GETPIVOTDATA() function to access pivot table data.
Regardless of trying to reference pivot table headers local to the workbook or as absolute values, I wasn't able to make it cooperate.
As another misfortune, you can't create a table which explicitly references another. So while you can create a new column with cells referencing cells, any expansion or contraction of the table may cause those outside cells to become inaccurate.