Westergaard, G. C., Lindquist, T. 1987. Manipulation of objects in a captive group of lion-tailed macaques (Macaca silenus). American Journal of Primatology 12, 231-234.

The animals frequently manipulated simple objects [browse and bamboo poles] that were provided in their home cage. They engaged in a variety of goal-oriented manipulative activities [e.g., to apply leverage, to create perches and ladders], with some instances involving joint action or social use.