That's tricky because the genders of many authors are unknown, and anyone who says they can tell when it's a man is lying.
i'm sorry, any time i see pointy balloon boobs i assume it's written by a man
The best way to tell is how the characters are written, but even that is just a guess. It's not like there are zero examples of emotionally complex character-driven yuri written by males and I've seen the opposite prove true as well on occasion. Most of the authors I consider female I can't even remember where I got that idea from. It could be anything from random internet conjecture to a proper public reveal but I just don't remember. I'ld hate to list a load of titles only to have it come back later that I was wrong on half of them.
