Physical description for original version: viii, 32 p. : 28 cm
書誌注記
Includes bibliographical references (p. 30-31)
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 : Books and Open-File Reports Section, U.S. Geoglogical Survey [distributor], 1990