I am trying to integrate ngx-admin with firebase. i have install firebase in my angular project.but it gives me such error "typescript error cannot find module 'firebase/app'." i have try to install typing also but doesn't got any luck

my stackstrace 

```
D:\admin-ionic> ng serve
Your global Angular CLI version (1.6.1) is greater than your local
version (1.4.9). The local Angular CLI version is used.

To disable this warning use "ng set --global warnings.versionMismatch=false".
** NG Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **
Date: 2017-12-21T08:36:34.546Z
Hash: ecdd99ad138ea0774dff
Time: 8026ms
chunk {inline} inline.bundle.js, inline.bundle.js.map (inline) 5.83 kB [entry] [rendered]
chunk {main} main.bundle.js, main.bundle.js.map (main) 1.06 kB {vendor} [initial] [rendered]
chunk {polyfills} polyfills.bundle.js, polyfills.bundle.js.map (polyfills) 323 bytes {inline} [initial] [rendered]
chunk {styles} styles.bundle.js, styles.bundle.js.map (styles) 694 kB {inline} [initial] [rendered]
chunk {vendor} vendor.bundle.js, vendor.bundle.js.map (vendor) 338 kB [initial] [rendered]

ERROR in D:/admin-society/node_modules/angularfire2/firestore/observable/fromRef.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firebase.app.module.d.ts (3,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firestore/collection/collection.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firestore/document/document.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firestore/firestore.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firestore/collection/changes.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/firestore/interfaces.d.ts (2,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/auth/auth.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/database/interfaces.d.ts (1,27): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/database/database.d.ts (1,26): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/database/list/state-changes.d.ts (3,26): Cannot find module 'firebase/app'.
ERROR in D:/admin-society/node_modules/angularfire2/database/list/audit-trail.d.ts (3,26): Cannot find module 'firebase/app'.
ERROR in Error: Metadata version mismatch for module D:/admin-society/node_modules/angularfire2/index.d.ts, found version 4, expected 3, resolving symbol AppModule in D:/admin-society/src/app/app.module.ts, resolving symbol AppModule in D:/admin-society/src/app/app.module.ts, resolving symbol AppModule in D:/admin-society/src/app/app.module.ts
    at syntaxError (D:\admin-society\node_modules\@angular\compiler\bundles\compiler.umd.js:1729:34)
    at simplifyInContext (D:\admin-society\node_modules\@angular\compiler\bundles\compiler.umd.js:24979:23)
    at StaticReflector.simplify (D:\admin-society\node_modules\@angular\compiler\bundles\compiler.umd.js:24991:13)
    at StaticReflector.annotations (D:\admin-society\node_modules\@angular\compiler\bundles\compiler.umd.js:24418:41)
    at _getNgModuleMetadata (D:\admin-society\node_modules\@angular\compiler-cli\src\ngtools_impl.js:138:31)
    at _extractLazyRoutesFromStaticModule (D:\admin-society\node_modules\@angular\compiler-cli\src\ngtools_impl.js:109:26)
    at Object.listLazyRoutesOfModule (D:\admin-society\node_modules\@angular\compiler-cli\src\ngtools_impl.js:53:22)
    at Function.NgTools_InternalApi_NG_2.listLazyRoutes (D:\admin-society\node_modules\@angular\compiler-cli\src\ngtools_api.js:91:39)
    at AotPlugin._getLazyRoutesFromNgtools (D:\admin-society\node_modules\@ngtools\webpack\src\plugin.js:212:44)
    at _donePromise.Promise.resolve.then.then.then.then.then (D:\admin-society\node_modules\@ngtools\webpack\src\plugin.js:448:24)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)

webpack: Failed to compile.

```

Here is my code

environment.ts

```
export const environment = {
  production: false,
  firebase : {
    apiKey: '***************************************',
    authDomain: 'ionicadmin-123456.firebaseapp.com',
    databaseURL: 'https://ionicadmin-123456.firebaseio.com',
    projectId: 'ionicadmin-123456',
    storageBucket: 'ionicadmin-123456.appspot.com',
    messagingSenderId: '123456789123',
  },
};

```

app.module.ts

```
@NgModule({
  declarations: [AppComponent],
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    HttpModule,
    AppRoutingModule,
    AngularFireModule.initializeApp(environment.firebase),
    AngularFirestoreModule, // imports firebase/firestore, only needed for database features
    AngularFireAuthModule, // imports firebase/auth, only needed for auth features
    NgbModule.forRoot(),
    ThemeModule.forRoot(),
    CoreModule.forRoot(),
  ],
  bootstrap: [AppComponent],
  providers: [
    { provide: APP_BASE_HREF, useValue: '/' },
  ],
})

```

committee.component.ts

```
import { Component } from '@angular/core';
import { AngularFirestore } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Observable';

@Component({
  selector: 'ngx-chartjs',
  styleUrls: ['./committee.component.scss'],
  templateUrl: './committee.component.html',
})
export class CommitteeComponent {
  items: Observable<any[]>;
  constructor(db: AngularFirestore) {
    this.items = db.collection('items').valueChanges();
  }
}

```

committee.component.html

```
<ul>
    <li *ngFor="let item of items | async">
      {{ item.name }}
    </li>
  </ul>

```