1. Putkaradze V, Rogers S (2017) On the optimal control of a rolling ball robot actuated by internal point masses.
arXiv:1708.03829
2. Sphero, ed. BB-8 by Sphero (2015)
https://brandfolder.com/bb8/attachments/926upng2/bb-8-by-sphero-bb-8-rolling-2-genericfile.jpg?dl=true&resource_key=mln615o60934&resource_type=Brandfolder
. Accessed 24 Aug 2017
3. Hernández JD (2013) Moisture measurement in crops using spherical robots. Ind Robot: Int J 40(1):59–66
4. Poincaré H (1901) Sur une forme nouvelle des équations de la mécanique. CR Acad Sci 132:369–371
5. Hamel G (1904) Die Lagrange–Euler’schen gleichungen der mechanik. Z Math Phys 50:1–57