There is an actual art (and science) to deal making. And after three-plus weeks of government shutdown, it should be clear by now if it wasnt already that President Donald Trump is uniquely terrible at the practice.

Trump is so out of the ordinary when it comes to negotiation, in fact, that the quarterly published by the Program on Negotiation at Harvard Law School, devoted its latest issue to him. For the first time in the Negotiation Journals 35-year history, its used a whole issue to talk about a U.S. president.

Due out next week, the Journal drills into the central paradox of Trump and negotiation: The president spent his career positioning himself as the consummate deal-maker. Hes listed as the author, after all, of the Art of the Deal, though it was ghost-written . Yet, theres little evidence hes actually good at deal-making. Many of his best real-estate deals were actually put in place by George Ross (who handled real estate negotiations), and Roy Cohn, the legendary attorney, was Trumps original fixer and known for being a brutal negotiator, writes University of Pennsylvania Wharton School professor G. Richard Shell in a piece for the issue.

Without Cohn, who died in 1986, there have been mostly business failures and bankruptcies and lawsuits.

In the close to 15 years that Ive been editing the Journal, nobody has used Donald Trump s the Art of the Deal as a citation in their article. Never. Not once, said Nancy Waters, the managing editor of the Journal, which is the publication for the Program on Negotiation, a consortium that includes Massachusetts Institute of Technology and Tufts University.

The omission was not out of elitism. Waters said that the publication, which has contributors across disciplines from around the globe, has covered other more pop-culture-esque business books. Trumps just never turned up.

That may be because Trumps negotiating style at a base level contradicts all the best practices generally agreed on by experts in negotiation.

The way he negotiates directly challenges what is almost a half-century of tools and principles and methods that have emerged in the field, said Joel Cutcher-Gershenfeld, a professor in the Heller School for Social Policy and Management at Brandeis University, who is the editor of the Journal.

To start, Trump claims to use a zero-sum strategy in which he wins and the other side loses. The win-lose equation is considered out of date, ineffective and generally counterproductive among those who study negotiation.