Usability and Utility of a Mobile App to Deliver Health-Related Content to an Older Adult Population: Pilot Noncontrolled Quasi-Experimental Study oleh Marta Lemos, Ana Rita Henriques, David Gil Lopes, Nuno Mendonça, André Victorino, Andreia Costa, Miguel Arriaga, Maria João Gregório, Rute de Sousa, Helena Canhão, Ana M Rodrigues