Find online books by searching topics like these and limiting the results to ebooks:
su: Environmentalism in literature.
su: Nature in literature.
su: ecology in literature.
Question: Why would you use Google Scholar?
Answer: Google Scholar identifies scholarly research materials from a broad range of subject areas.
Google Scholar offers a "cited by" feature - it will display a list of documents which cited the document you originally retrieved. This can be useful in determing how influential a source has been. The list only includes documents available in Google Scholar, though.
Go into the preferences of Google Scholar and select Pepperdine University from Library Links.