Unable to refer external module in TypeScript -

i want use external module in typescript code, failing. specifically, want use methods referring external.d.ts file in typescript script.

my code is:

module test {      //this not working. want know syntax refer express here.     private express: typeof express = require("express");      export testserver     {         constructor(private app:express.application)         {           //can not find express symbol         }     } 

//this not working. want know syntax refer express here. private express: typeof express = require("express"); 

use import:

  import express = require("express");    export testserver   {        constructor(private app:express.application)        {        }   } 

and don't mix internal , external modules. more in youtube video typescript modules demystified: internal, amd requirejs, commonjs node.js.