http://plnkr.co/edit/Aa8O6lAh9lsOo3qk8gYZ?p=preview

https://stackoverflow.com/questions/43383341/angular-2-reactive-form-validation-messages

https://stackoverflow.com/questions/42184800/how-to-validate-formarray-length-in-angular2

https://medium.com/@mihalcan/angular-multiple-check-boxes-45ad2119e115

http://www.syntaxsuccess.com/viewarticle/recursive-treeview-in-angular-2.0

https://angular2-tree.readme.io/docs/async-data-1

https://scotch.io/tutorials/authenticate-a-node-js-api-with-json-web-tokens

http://jasonwatmore.com/post/2016/12/08/angular-2-redirect-to-previous-url-after-login-with-auth-guard

https://stackoverflow.com/questions/34331478/angular-redirect-to-login-page

https://dzone.com/articles/build-your-nodejs-application-in-a-modular-way

https://github.com/brechtbilliet/largescale_apps

https://medium.com/@ttemplier/angular2-decorators-and-class-inheritance-905921dbd1b7

https://spin.atomicobject.com/2017/04/24/typescript-modular-typesafe-metadata/

Reflect JS library, Decorator Typescript Dynamic Form and Component in Angular 5 MongoDB and Express based on NodeJS, Lazy load module

Npm link not working with lazy module loader via router Take a lot of time to resolve issues of npm link and angular -cli