You can include contents to your projects by making a reference to a supported external content source. The Document! X takes the latest content that is referenced from an external source when you preview or build your project. 

The following external sources are currently supported:

• Quip Document: Quip is a simple collaborative document editor that makes it easy for multiple users to work on a document. Quip includes a threaded revision and comment capability that makes it easy to track revisions and discuss document revisions.
• Web Page: Include content from a web page. The whole page can be used, or the content of a specific part of the page.