IS THERE A DOCTOR IN THE HOUSE? (need sources to prove to someone that trans people are real scientifically) ikr...ugh

I need peer reviewed sources from reputable institutions to prove to an old cis white guy-(who is my boss) that trans people exist along with a myriad of other topics like: gender fluidity, sexual fluidity, non-heteronormativity, etc... basically I need to give a well formatted and sourced sex-ed class to this guy and I don't have the knowledge or resources to do so. I also don't wanna just not rise to his challenge cause I think that'll make him more polarized. if anyone could reply with individual documents or fonts of knowledge I would be very grateful. Hope to hear from all ya'll.