Refinement and Usability Analysis of an eHealth App for Ankylosing Spondylitis as a Complementary Treatment to Physical Therapy: Development and Usability Study - Nitschke, Marlies; Nwosu, Obioma Bertrand; Grube, Lara; Knitza, Johannes; Seifer, Ann-Kristin; Eskofier, Bjoern M.; Schett, Georg; Morf, Harriet (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2023)