Thanks to a VERY deep undercover agent in the field (in academia!), I think I have found the perfect, singular and AUTHORITATIVE source to point young women to when they claim there's a wage gap, women earn less than men, glass ceiling, etc. etc. etc.
It's a PDF file, but in short it is a 182 page paper on earnings potentials for different degrees. You needed read the entire document (obvious) as much as just peruse the charts in the first few pages. It's DAMNING as to just how clear it is that women simply choose:
More popular and thus
More supplied/flooded majors
which (if they ever bothered to pay attention to economics 101, but "math hard") explains not only the wage gap, BUT PROVIDES THE THE KEY IF THEY WISH TO CLOSE IT! (but again, I know, I know, "math hard")
Anyway, book mark this page and merely link to it anytime you get into this tiresome and obsolete argument that there's a wage gap.