Zander‘s 1925 paper, “Problems of flight by jet propulsion: interplanetary flights,” was translated by NASA. See NASA Technical Translation F-147 (1964); specifically, Section 7: Flight Around a Planet’s Satellite for Accelerating or Decelerating Spaceship, pp. 290-292.
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Romanovskis, T (2004). "Comment on Families of Keplerian orbits". European Journal of Physics. 25 (2): L17 –L19. doi:10.1088/0143-0807/25/2/L03.
Siddiqi, Asif (2004). "Deep Impact: Robert Goddard and the Soviet 'Space Fad' of the 1920s". History and Technology. 20 (2): 97–113. doi:10.1080/0734151042000240782. S2CID145523726.
Another distinguished German from Riga was Friedrich Zander (1887-1933), who graduated from the Mechanics Department of Riga Polytechnic Institute in 1914 and remained there to pursue research which culminated in the construction of the first rocket., Contribution of Baltic Germans to Science The Latvian Institute
Siddiqi, Asif (2004). "Deep Impact: Robert Goddard and the Soviet 'Space Fad' of the 1920s". History and Technology. 20 (2): 97–113. doi:10.1080/0734151042000240782. S2CID145523726.