Ask Dr. Universe: Why do apes walk on their knuckles? | The Spokesman-Review
The Origins of Walking | North Carolina Zoo
The biomechanical importance of the scaphoid-centrale fusion during simulated knuckle-walking and its implications for human locomotor evolution | Thomas A. Püschel
Western lowland gorilla - Tierpark Hellabrunn
Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor | PNAS
News in Science - We used to walk on our knuckles - 23/03/2000
Figure 1 from Origin of human bipedalism: The knuckle-walking hypothesis revisited. | Semantic Scholar
A Silverback Gorilla Knuckle-Walking Stock Photo - Image of endangered, expressive: 113337686
Knuckle Walking by artists Gillie and Marc – Love the Last