Button To Move To The Previous Page

I am trying to put a buuton into my page which will take the user back to the previous page. The reason i am doing this is that the user may come to this page from more than one other page.

I am using this code for the button, which i have seen on many code examples, but when i click on the button, it results in an error as if the existing page is trying to load itself up again.

<form>
<td width = "325" align="left">
<input type="submit" name="back" value="Back" onClick="javascript: history.go(-1)">
</td>
</form>

have also tried using the javascript: history.go(-1) code in the form declaration as the onSubmit attribute, but this just makes the same page load up again.