Cannot find module 'rxjs/subject/BehaviorSubject'
<p>I am using Angular 2.</p>

<p>When I use either of these two, my program runs well:</p>

<pre><code>import { BehaviorSubject } from 'rxjs/Rx';
import { BehaviorSubject } from 'rxjs';
</code></pre>

<p>However, I try to use the following way:</p>

<pre><code>import { BehaviorSubject } from 'rxjs/subject/BehaviorSubject';
</code></pre>

<p>But I failed, my browser console shows:</p>

<blockquote>
  <p>Uncaught Error: Cannot find module 'rxjs/subject/BehaviorSubject'</p>
</blockquote>

<p>How can I use third way correctly? Thanks</p>