On audible, both the Gray series and one of my Oil Apocalypse series are currently on sale. 

As both of these are published by trade publishers, not myself, I am not 100% certain how long these sales will last. For Gray, you need only to go to your favorite sales outlet.

For Desolated, you need to follow this link:

https://www.audiobooks.com/promotions/promotedBook/436103/desolated?refId=57242

Thank you for listening, reading, and recommending my books to your friends!