When did Warehouse 13 reference John Ringo’s novels?

Question

The Acknowledgments of John Ringo’s new novel Queen of Wands states:

I’d like to thank the writers and producers [of Warehouse 13] for not only making a really good television show (words that are very hard for me to type as they’re so uncommon) but for featuring my novels in one of the backgrounds. [clarification & emphasis added]

To what does the phrase I’ve boldfaced refer?

Answer 1

Thaddeus is correct - in the episode "Emily Lake" (season 3, episode 11) at the 12:40 mark, there is a copy of Eye of the Storm on the book shelf in the background.

Answer 2

I unfortunately cannot tell you the episode it appears in but the shout-out is for showing an episode featured a copy of John Ringo's Eye of the Storm in the background on a bookshelf. I am going through my Warehouse 13 collection to see if I can find a screenshot. Ringo repaid the nod with a cameo in Queen of Wands for Artie and Claudia bagging an artifact.