title: Angular 2: Cannot find module 'angular2/core'
body: <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>