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