There are more ...LOL...the "American College of Pediatricians" is an anti-LGBTQ advocacy group that opposes adoption by gays or lesbians and advocates for "conversion therapy". GTFO with that BS.
PBS
BBC
The Lancet
Admittedly there are other sources that will tell you puberty blockers are considered safe, including hospitals (not surprising). But then, like St. Louis Children's Hospital, give a long list of both short-term and long-term side effects:
SLCH