"Gender-Affirming Psychiatric Care," just released on Amazon at $58, is a textbook printed by American Psychiatric Association (APA) Publishing.

The textbook signals early on that it's more subjective than objective, quoting a feminist studies professor saying, "Scientific neutrality is a fallacy."

The content has prompted some critics to question the textbook's reliance on a mix of transgender-identifying professionals writing about their experiences, limited scientific studies, and neo-Marxist critical theories.

"This is a huge issue; millions more kids will be harmed," said Dr. Lauren Schwartz, a psychiatrist in Oklahoma speaking out against the rush to "transition" children.