One scholar’s critical book on the transgender movement has reportedly been removed from Amazon.com.

On Sunday afternoon, Ryan Anderson—the current president of the Ethics and Public Policy Center (EPPC)—reported that his book When Harry Became Sally: Responding to the Transgender Moment was no longer listed for purchase on the online retail giant Amazon.com. The book was released three years ago, on Feb. 20, 2018.

“And not just like it‘s out of stock. The pages are down. You can’t buy a used copy. You can‘t buy the kindle. You can’t get the Audible version,” Anderson told CNA. He said that his book’s publisher asked for an explanation from Amazon as to why it was not being listed online, but had not yet received an explanation.

Anderson’s book was commended by professors of psychiatry, psychology, and medical ethics at universities such as Johns Hopkins, Boston University, New York University, and Columbia University.

Despite the acclaim from scholars, he said it was still de-listed at Amazon. “It’s not about how you say it, it’s not about how rigorously you argue it, it’s not about how charitably you present it. It’s about whether you dissent from a new orthodoxy,” he said.