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Söker en 1970-talet (eller tidigare) roman som inbegriper tidsresor och ekologisk bevarande. Från beskrivningen som tillhandahålls:
It involved time travel (unexplained) with a girl, from a future so polluted that there weren't any animals but humans any more, traveling back in time to the mid-20th century and meeting her grandfather or great-grandfather or some such who would grow up to be a famous conservationist. She tries to fit in in the new time and fails.
she finds her way home, and her ancestor gives her some animals to take with her. I specifically remember wolf cubs. (I did not, at that age, wonder what on earth wolves would eat if the future folks ever tried to establish a wild population again. Now... I do wonder. I wonder about lack of genetic diversity, too.)
The copy I read didn't have a dust jacket. I'm pretty sure the cover was light, between white and yellow, and the art was in shades of gray and showed the main character and possibly some animals.