Automatically appending two tables of data into a third table

I found this information and spreadsheet example potentially very useful. However, I'm having trouble adapting this if the tables to append from are on separate worksheets. I have the "F" column (key) set up OK on tables 1, 2, and 3 when they're on separate worksheets, but I don't seem to know how to make the cell references in Table 3 (columns c, d, and e) go across multiple sheets. any ideas?