You can make related documents linked together by making references. It makes exploring documents easier.
Add Reference
To add a referenced document, click on the 
button from the action bar, and find the related document,
Select them by making the checkbox on the first column checked, and at the end click on the
button.
Remove Reference
To remove a reference to another document, select the document from the list first, click on the 
button, if you are sure about it, click on a 
button.
Open a Reference
To get more information about a referenced document, you can select it from the list then click on the
button.
Go back to the documents list
If you need to go back to see the list of the documents you can click on the
button from the right side of the action bar.