Ludin, D., W. Wellbrock, E. Müller, W. Gerstlberger, K. Kljevkovic, and D. Michel. “The Necessity of Domestic Flights at Business Trips — A Theoretical and Empirical Study Under the Aspect of Climate-Friendly Alternatives”. Journal of Strategic Innovation and Sustainability, vol. 16, no. 3, Aug. 2021, doi:10.33423/jsis.v16i3.4439.