Patients’ Experiences of a National Patient Portal and Its Usability: Cross-Sectional Survey Study - Saija Simola; Iiris Hörhammer; Yuhui Xu; Annika Bärkås; Asbjørn Johansen Fagerlund; Josefin Hagström; Mari Holmroos; Maria Hägglund; Monika Alise Johansen; Bridget Kane; Anna Kharko; Isabella Scandurra; et al. (Journal of Medical Internet Research, 2023)