Manning have a set of PowerShell books on their deal of the day for 9 December 2015. The deal includes:
Windows PowerShell in Action, Third Edition
PowerShell and WMI
PowerShell Deep Dives
Powershell in Depth, Second Edition
PowerShell in Practice
Learn Windows PowerShell in a Month of Lunches, Second Edition
The deal will go live at Midnight US ET and will stay active for ~48 hours.
Get 50% off these books with code dotd120915au at manning.com