I have a reference who works at the company I'm applying for. She and I have known each other for over a decade and are close friends, but we also were officers in a major club together in high school (I was president and she was secretary and we and a handful of other officers were in charge of approximately 50 students). How do I list our relationship without making it seem unprofessional? I have another reference from an actual job I've worked at, but I don't want to just have the one.