Three years into the pandemic: results of the longitudinal German COPSY study on youth mental health and health-related quality of life oleh Ulrike Ravens-Sieberer, Janine Devine, Ann-Kathrin Napp, Anne Kaman, Lynn Saftig, Martha Gilbert, Franziska Reiß, Constanze Löffler, Anja Miriam Simon, Klaus Hurrelmann, Sabine Walper, Robert Schlack, Heike Hölling, Lothar Heinz Wieler, Lothar Heinz Wieler, Michael Erhart, Michael Erhart, Michael Erhart