Tilling, Robert I., Topinka, Lyn and Swanson, Donald A. Eruptions of Mount St. Helens: Past, Present, and Future. The Climactic Eruption of May 18, 1980. U.S. Geological Survey (Special Interest Publication). 1990 [2013-06-20]. (原始内容存档于2011-10-16). (adapted public domain text)
Tilling, Robert I., Topinka, Lyn and Swanson, Donald A. Eruptions of Mount St. Helens: Past, Present, and Future. The Climactic Eruption of May 18, 1980. U.S. Geological Survey (Special Interest Publication). 1990 [2013-06-20]. (原始内容存档于2011-10-16). (adapted public domain text)