"Conservation." . . "Examines the causes of pollution in air, water, and soil and the long-range effect upon human and animal life."@en . "Examines the causes of pollution in air, water, and soil and the long-range effect upon human and animal life." . . "The only earth we have"@en . "The only earth we have" . . . . . "Juvenile works" . . "Juvenile works"@en . . . . . . . . . . .