The following are some references:
- NestJS official website: https://nestjs.com
- NestJS Sources: https://github.com/nestjs/nest
- Express API: https://expressjs.com/en/4x/api.html
- CLI overview: https://docs.nestjs.com/cli/overview
- CLI usage: https://docs.nestjs.com/cli/usages
- Modules: https://docs.nestjs.com/modules
- Providers: https://docs.nestjs.com/providers
- Controllers: https://docs.nestjs.com/controllers