Robert F. Black (1976). "Geology of Umnak Island, Eastern Aleutian Islands as Related to the Aleuts". Arctic and Alpine Research. 8 (1): 7–35. doi:10.2307/1550607. JSTOR1550607.
Robert F. Black (1976). "Geology of Umnak Island, Eastern Aleutian Islands as Related to the Aleuts". Arctic and Alpine Research. 8 (1): 7–35. doi:10.2307/1550607. JSTOR1550607.