Angular 2: Cannot find module 'angular2/core'
<p>I'm having a problem with Angular 2 + Typescript, whenever I try to gulp build it shows me the same errors, I have tried everything including putting the &lt;reference&gt; tags in the files. What to do?</p>

<blockquote>
<pre><code>(7,26): error TS2307: Cannot find module 'rxjs/Rx'./Users/macbook/workspace/rss/src/app/services/rootscope.ts
(8,46): error TS2307: Cannot find module 'angular2/core'./Users/macbook/workspace/rss/src/app/services/rootscope.ts
(17,48): error TS2304: Cannot find name 'Observer'./Users/macbook/workspace/rss/src/app/services/api.ts
(6,26): error TS2307: Cannot find module 'angular2/core'./Users/macbook/workspace/rss/src/app/services/api.ts
(7,27): error TS2307: Cannot find module 'angular2/http'./Users/macbook/workspace/rss/src/app/services/api.ts
(15,13): error TS2339: Property 'http' does not exist on type 'API'./Users/macbook/workspace/rss/src/app/services/api.ts
(19,20): error TS2339: Property 'http' does not exist on type 'API'./Users/macbook/workspace/rss/src/app/services/api.ts
(23,20): error TS2339: Property 'http' does not exist on type 'API'../src/app/app.ts
(6,25): error TS2307: Cannot find module 'angular2/platform/browser'../src/app/app.ts
(7,25): error TS2307: Cannot find module 'angular2/core'../src/app/app.ts
(8,47): error TS2307: Cannot find module 'angular2/http'. 
</code></pre>
</blockquote>

<p><strong>rootscope.ts</strong></p>

<pre><code>/// &lt;reference path="../../../node_modules/reflect-metadata/reflect- metadata.d.ts" /&gt;
/// &lt;reference path="../../../node_modules/angular2/typings/browser.d.ts" /&gt;
/// &lt;reference path="../../../node_modules/angular2/core.d.ts" /&gt;
/// &lt;reference path="../../../node_modules/angular2/http.d.ts" /&gt;
/// &lt;reference path="../../../node_modules/rxjs/Rx.d.ts" /&gt;

import {Observable} from "rxjs/Rx";

import {Injectable,EventEmitter,Output} from "angular2/core";

@Injectable()
export class ROOT_SCOPE {
  data: any;
  dataChange: Observable&lt;any&gt;;
  @Output dataChangeObserver: EventEmitter=new EventEmitter();

  constructor() {
    this.dataChange = new Observable((observer:Observer) =&gt; {
      this.dataChangeObserver = observer;
    });
  }

  set(data:any) {
    this.data = data;
    this.dataChangeObserver.next(this.data);
  }
}
</code></pre>