Piper, P. J.; Ochoa, J.; Lewis, H.; Paz, V.; Ronquillo, W. P. (2008). “The first evidence for the past presence of the tiger Panthera tigris (L.) on the island of Palawan, Philippines: extinction in an island population”. Palaeogeography, Palaeoclimatology, Palaeoecology. 264: 123–127. doi:10.1016/j.palaeo.2008.04.003.