Amazon has stopped selling books on therapies that attempt to alter the sexual orientation or gender identity of lesbian, gay, bisexual and transgender people written by NARTH founder Joseph Nicolosi.

Such therapies go by names such as “conversion therapy,” “reparative therapy,” “sexual orientation change efforts” or “ex-gay therapy.” Seventeen states plus the District of Columbia have banned such therapies to minors.

(Related: Utah's governor issues directive to regulate “ex-gay” therapy.)

Nicolosi, who died in 2017, founded the National Association for Research & Therapy of Homosexuality (NARTH) in 1992 with Benjamin Kaufman and Charles Socarides. NARTH, which changed its name to the Alliance for Therapeutic Choice and Scientific Integrity (ATCSI) in 2014, was a response to the removal of homosexuality from the Diagnostic and Statistical Manual of Mental Disorders (DSM), a publication of the American Psychiatric Association (APA) that classifies mental disorders.

According to Business Insider, Amazon has pulled titles by Nicolosi such as Healing Homosexuality and A Parents' Guide to Preventing Homosexuality. The outlet cites “sustained pressure from activists” as the reason for Amazon's move.

Nicolosi told The New York Times in 2012 that he believes “all people are heterosexual, but that some have a homosexual problem.”

“I don't believe anyone is really gay,” he told the outlet at the time.