How to use referrer url in

I want to load some scripts only when traffic from a particular hostname. For example: I will load a script when blog traffic from www.mywebsite2.com. How can i do that. I tried a lot but couldn't find anything related to that.

Here are some codes that i have tried.

<b:if cond='"referrer" == "www.mywebsite2.com"'>
     <script>...</script>
    <b:else/>
      <script>...</script>
    </b:if>

How can i use the referrer in that.