Physical description for original version: vi, 51 p. : 29 cm
書誌注記
Includes bibliographical references (p. 49-51)
原資料等に関する注記
原資料の出版事項: Reston, Va. ; Denver, CO : U.S. Dept. of the Interior, U.S. Geological Survey : For sale by U.S. Geological Survey, Branch of Information Services, 1999