Helfrich, H. W. (1970). The environmental crisis. Yale University Press.
Chicago Style (17th ed.) CitationHelfrich, Harold W. The Environmental Crisis. New Haven [etc.]: Yale University Press, 1970.
MLA (9th ed.) CitationHelfrich, Harold W. The Environmental Crisis. Yale University Press, 1970.
Warning: These citations may not always be 100% accurate.