Create Chart in Excel 2003 Using Data from Multiple Worksheets

I have been failing while trying to create a chart from three worksheets named a, b, and c.
The data I want on chart is from cell F5 on each sheet.

What is the Data Range Syntax to create this chart? I’ve tried “=’a!$F$%,b!$F$5,c!$F$5′ and “=’a:c’!F5

Any ideas is appreciated!

Keith