Physical description for original version: 44 p. : 28 cm
書誌注記
Includes bibliographical references (p. 3-4)
原資料等に関する注記
原資料の出版事項: St. Paul, Minn. (1992 Folwell Ave., St. Paul 55108) : North Central Forest Experiment Station, Forest Service, U.S. Dept. of Agriculture, 1986