1. “Behind the Sputniks: A Survey of Soviet Space Science.”;Tsiolkovsky,1958
2. “Beyond the Planet Earth.”;Konstantin,1960
3. “Konstantin Tsiolkovsky.”;Kosmodemyansky,1956
4. “Die Rakete zu den Planetenräumen,”;Oberth,1923
5. “Wege zur Raumschiffahrt,”;Oberth,1929