"Hokkaido". Seamless Digital Geological Map of Japan. Geological Survey of Japan, AIST. 2007. Archived from the original on 2013-01-06. Retrieved 2010-09-28.
"MASHU-KO (LAKE MASHU)". World Lakes Database. International Lake Environment Committee. Archived from the original on 2012-02-29. Retrieved 2008-10-15.
lake-akan.com
"Lake Mashu". Highlights: Eastern Hokkaido. Akan Tourism Association & Community Development Promotion Organization. Retrieved 2008-10-15.
"MASHU-KO (LAKE MASHU)". World Lakes Database. International Lake Environment Committee. Archived from the original on 2012-02-29. Retrieved 2008-10-15.
"Hokkaido". Seamless Digital Geological Map of Japan. Geological Survey of Japan, AIST. 2007. Archived from the original on 2013-01-06. Retrieved 2010-09-28.