As fears about the expansion of ISIS, the Islamic State in Iraq and Syria, continue to mount, two publishers are rushing books about the militant terrorist group to market.

Tuesday, Ecco announced that it acquired world rights to ISIS: The State of Terror by Jessica Stern and J.M. Berger, and plans to publish the book in January 2015. Daniel Halpern, president and publisher of Ecco, an imprint of HarperCollins, negotiated the deal with Martha Kaplan of the Martha Kaplan Agency.

Stern is a Lecturer on Terrorism at Harvard University and author of Denial: A Memoir of Terror, as well as Terror in the Name of God: Why Religious Militants Kill; Berger is the author of Jihad Joe: Americans Who Go to War in the Name of Islam. Ecco said the pair will draw on their "unusual access to intelligence sources and material, law enforcement, and groundbreaking research into open source intelligence" to outline the origins of ISIS as the "formidable terrorist group it has quickly become."

Howard Books, an imprint of Simon & Schuster, had already signed up attorney Jay Sekulow to write a handful of e-shorts, and the week before Labor Day, Sekulow suggested ISIS as a potential topic. His 30,000 word e-short, Rise of ISIS: A Threat We Can't Ignore, went on sale on September 15, and the publisher will be crashing a print version, set to publish as a paperback, on October 14.

The preoders for the e-book version of Rise of ISIS came to 5,000 without any national media, according to Jonathan Merkh, v-p and publisher at Howard. The preoder numbers for the paperback are even stronger; they have reached 175,000, and are "climbing daily."

Sekulow will appear on Hannity on September 17, which will kick off a national media campaign that will last for "weeks," according to Merkh. "In less than two weeks we've been able to get broad distribution in every book outlet from the bookstore chains, to the big boxes, e-tailers, airports and also the Christian market," he added.

"The subject is not going away," said Merkh. "As Jay says himself, 'This is a war that will not end' based on what ISIS plans on doing."