Quick, clean, and to the point

Go to previous workbook

Windows shortcut 
Mac shortcut 

Move to next / previous workbook window.

Note: in Mac 2016, Control + shift+ tab stopped working. However, Command + shift + ` will go to the previous workbook.

Related videos

The videos below demonstrate this shortcut.
In this lesson, we cover shortcuts you can use to navigate workbooks.
In this video, we find your way around a an Excel workbook, and how to see where you are now.