The necessity of domestic flights at business trips - A theoretical and empirical study under the aspect of climate-friendly alternativesLudin, Daniela; Wellbrock, Wanja; Gerstlberger, Wolfgang Dieter; Mueller, Erika; Kljevkovic, Kristina; Michel, DanielICSD 2020 : 2020 International Conference on Sustainable Development (ICSD), 21st – 22nd September : proceedings : online2020 / 16 p. : ill https://ic-sd.org/wp-content/uploads/2020/11/Daniela-Ludin.pdf