If a page 'A' is opened, find out from which source page page 'A' has been called?

[quadmud]

I am currently in "pageA.aspx". Using \[code\]top.location.href\[/code\] or \[code\]Response.Redirect()\[/code\], I've come to "pageB.aspx". How to find out that which page has called "pageB.aspx". Is it "pageA.apsx" or any other page.I aware of using URL Query-String. But I need to use any other option.