1. Weird Robots to Explore the Moon;Griswald;Popular Science Magazine,1962
2. Theory of Land Locomotion;Bekker,1957
3. Transportation;St. Clair,1934
4. A Story About Walking Machines;Hutchinson;Chairman's Address to the Eastern Branch of the Institution of Mechanical Engineers,1962
5. Tanks That Walk and Jump;Mann;Popular Science Magazine,1960