To make sure I give you exactly what you need, could you clarify which of these you were interested in?
: Are you looking for information, articles, or profiles on mature female athletes and muscle maturity in the context of professional bodybuilding? mature female muscle
It looks like your request for "proper paper: 'mature female muscle'" could refer to a few different things depending on what you're looking for. To make sure I give you exactly what
: Are you seeking advice or "white paper" style guides on strength training and muscle maintenance for women over 50 or 60? mature female muscle