5G Vehicle-to-Everything Services in Cross-Border Environments: Standardization and Challenges. - Apostolos Kousaridas; Mikael Fallgren; Edwin Fischer; Francesca Moscatelli; Ricard Vilalta; Maciej Mühleisen; Sokratis Barmpounakis; Xavier Vilajosana; Sebastian Euler; Bruno Tossou; Jesus Alonso-Zarate (IEEE Commun. Stand. Mag., 2021)