Ellies Tunjung SM., S.ST., M.Si. and Dr. Supatmi, S.Kep.,Ns.,M.Kes and Siti, Mufarrohah and Desta, Driutama Identification Of Hematocrit Values In Teenagers Active Coffee Drinkers. Project Report. Universitas Muhammadiyah Surabaya. (Unpublished)