Gravity bias in young and adult chimpanzees (Pan troglodytes): Tests with modified opaque-tubes task.
Developmental Science, 10, 411-421
Behavior of infant chimpanzees during the night in the first 4 months of life: smiling and suckling in relation to behavioral state.
Infancy, 9(2): 215-234
Exploring by doing: How young chimpanzees discover surfaces through actions with objects
Infant Behavior & Development, 28, 316-328
How does stone-tool use emerge? Introduction of stones and nuts to naive chimpanzees in captivity.
Primates, 46(2): 91-102.
Development of social cognition in infant chimpanzees (Pan troglodytes): Face recognition, smiling, gaze, and the lack of triadic interactions
Japanese Psychological Research, Volume 46, Issue 3, pages 227-235