Before astropolitics: Ratzel, Schmitt, and the question of cosmic colonisation
https://www.cambridge.org/core/journals/review-of-international-studies/article/before-astropolitics-ratzel-schmitt-and-the-question-of-cosmic-colonisation/69F8E68C294610148FADBE3444C9579C
Journey into Space: ETH is reaching for the stars
https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/712244/Globe2404_Journey-into-space.pdf
Recent innovations to advance space electric propulsion technologies
https://www.sciencedirect.com/science/article/abs/pii/S0376042123000167