Cannot find type definition file for 'core-js'

I am building an angular2 application with angular-cli. angular-in-memory-web-api was not installed by default.

So I searched for it and added this line "angular-in-memory-web-api": "~0.1.5" in my package.json file. And did npm install.

Now I am having this issue.

ERROR in [default] /home/adil/Code/AngularJS.2/cli-based/mz-doc-app/node_modules/angular-in-memory-web-api/in-memory-backend.service.d.ts:1:0 
Cannot find type definition file for 'core-js'.

Please suggest some solution ?

package.json

{
  "name": "mz-doc-app",
  "version": "0.0.0",
  "license": "MIT",
  "angular-cli": {},
  "scripts": {
    "start": "ng serve",
    "lint": "tslint \"src/**/*.ts\"",
    "test": "ng test",
    "pree2e": "webdriver-manager update",
    "e2e": "protractor"
  },
  "private": true,
  "dependencies": {
    "@angular/common": "~2.1.0",
    "@angular/compiler": "~2.1.0",
    "@angular/core": "~2.1.0",
    "@angular/forms": "~2.1.0",
    "@angular/http": "~2.1.0",
    "@angular/material": "^2.0.0-alpha.9-3",
    "@angular/platform-browser": "~2.1.0",
    "@angular/platform-browser-dynamic": "~2.1.0",
    "@angular/router": "~3.1.0",
    "@types/core-js": "^0.9.34",
    "angular-in-memory-web-api": "~0.1.5",
    "core-js": "^2.4.1",
    "rxjs": "5.0.0-beta.12",
    "ts-helpers": "^1.1.1",
    "zone.js": "^0.6.23"
  },
  "devDependencies": {
    "@types/jasmine": "^2.2.30",
    "@types/node": "^6.0.42",
    "angular-cli": "1.0.0-beta.18",
    "codelyzer": "1.0.0-beta.1",
    "jasmine-core": "2.4.1",
    "jasmine-spec-reporter": "2.5.0",
    "karma": "1.2.0",
    "karma-chrome-launcher": "^2.0.0",
    "karma-cli": "^1.0.1",
    "karma-jasmine": "^1.0.2",
    "karma-remap-istanbul": "^0.2.1",
    "protractor": "4.0.9",
    "ts-node": "1.2.1",
    "tslint": "3.13.0",
    "typescript": "~2.0.3"
  }
}