Depending on which server-side language you are suing there is such a thing as a Referrer. Which contains the referring address, but this of course falls outside the scope of HTML.
Try a forum for the server side language you are using:
forum434
forum333
forum855
forum232
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Ignorance is not necessarily Bliss, case in point:
Unknown has caused an Unknown Error on Unknown and must be shutdown to prevent damage to Unknown.