Piper, Philip J.; Ochoa, Janine; Robles, Emil C.; Lewis, Helen; Paz, Victor (2011-03-15). “Palaeozoology of Palawan Island, Philippines”. Quaternary International (Elsevier) 233 (2): 142–158. Bibcode: 2011QuInt.233..142P. doi:10.1016/j.quaint.2010.07.009.
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, Palaeoecology264 (1–2): 123–127. Bibcode: 2008PPP...264..123P. doi:10.1016/j.palaeo.2008.04.003.
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Piper, Philip J.; Ochoa, Janine; Robles, Emil C.; Lewis, Helen; Paz, Victor (2011-03-15). “Palaeozoology of Palawan Island, Philippines”. Quaternary International (Elsevier) 233 (2): 142–158. Bibcode: 2011QuInt.233..142P. doi:10.1016/j.quaint.2010.07.009.
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, Palaeoecology264 (1–2): 123–127. Bibcode: 2008PPP...264..123P. doi:10.1016/j.palaeo.2008.04.003.