About Boston Dynamics. In: BostonDynamics.com. Abgerufen am 13. Dezember 2013 (englisch).
dtic.mil
apps.dtic.mil
Richard J. Barber Associates: The Advanced Research Projects Agency, 1958-1974. VI-41. In: Defense Technical Information Center. Dezember 1975, S. 358 f., abgerufen am 16. Mai 2020 (englisch): „the Agency also investigated various advanced vehicle concepts including work on a project variously known as a "mechanical elephant" or "mechanical horse" which was to move through servo-mechanism "legs"“
Hyunjoo Jin, Heekyong Yang: Hyundai Motor to buy controlling stake in U.S. robot firm from SoftBank. In: Reuters. 11. Dezember 2020 (reuters.com [abgerufen am 23. März 2021]).