Angularfire Uncaught ReferenceError: Firebase is not defined
<p>I'm following the example Getting started with Firebase and Angular - Firecasts #4 and I keep getting:</p>

<pre><code>Uncaught ReferenceError: Firebase is not defined.
</code></pre>

<p>Any ideas?</p>

<p>Here is my app.js:</p>

<pre class="lang-js prettyprint-override"><code>    angular
    .module('app', ['ngRoute', 'firebase'])
    .constant('FirebaseUrl', 'https://&lt;my-app&gt;.firebaseio.com/')
    .service('rootRef', ['FirebaseUrl', Firebase])
    .service('users', Users)
    .controller('MyCtrl', MyController)
    .config(ApplicationConfig);

function ApplicationConfig($routeProvider) {
    $routeProvider.when('/', {
        controller: 'MyCtrl as ctrl',
        templateUrl: 'views/myctrl.html'
    });
}

function Users(rootRef, $firebaseObject, $firebaseArray) {
    var usersRef = rootRef.child('users');
    this.get = function get(id) {
        return $firebaseObject(usersRef.child(id));
    };

    this.all = function all() {
        return $firebaseArray(usersRef);
    };
}

function MyController(users) {
    this.users = users.all();
}
</code></pre>

<p>This is my index.html:</p>

<pre class="lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
    &lt;html lang="en" ng-app="app"&gt;
     &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;AngularFire&lt;/title&gt;
    &lt;script src="bower_components/angular/angular.js"&gt;&lt;/script&gt;
    &lt;script src="bower_components/firebase/firebase.js"&gt;&lt;/script&gt;
    &lt;script src="bower_components/angular-route/angular-route.js"&gt;&lt;/script&gt;
    &lt;script src="bower_components/angularfire/dist/angularfire.js"&gt;&lt;/script&gt;
    &lt;script src="app.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;ng-view&gt;&lt;/ng-view&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>