1. US Geological Survey Fact Sheet 1997 United States Geological Survey (USGS) Lahars of Mount Pinatubo Philippines 114 197
2. US Geological Survey Fact Sheet 1997 United States Geological Survey (USGS) Benefits of volcano monitoring far outweigh costs: The case of Mount Pinatubo 115 197
3. US Geological Survey Fact Sheet 1997 United States Geological Survey (USGS) The cataclysmic 1991 eruption of Mount Pinatubo Philippines 113 197