External communication of automated shuttles: Results, experiences, and lessons learned from three European long-term research projects. - Alexander G. Mirnig; Magdalena Gärtner; Peter Fröhlich 003; Vivien Wallner; Anna Sjörs Dahlman; Anna Anund; Petr Pokorny; Marjan P. Hagenzieker; Torkel Bjørnskau; Ole Aasvik; Cansu Demir; Jakub Sypniewski (Frontiers Robotics AI, 2022)