With Google Scholar you can find books and journal articles. You can also find more books and articles closely related to the ones you have in hand. Google Scholar allows you to see what works have cited the book or article you have.
The challenge for research in Environmental Studies is that there is no single database that effectively covers the literature for all potential topics in Environmental Studies in sufficient depth. Use several databases to discover resources that relate to your topic.
Many of the databases listed on these pages cover a variety of publication types: books, journal articles, news & magazine articles, government reports & documents (international, federal, state), and unpublished research reports. The databases marked with a star 
will give you the best results, so start with those first.
General Databases:
Academic Search Complete -- A large database of mostly scholarly material covering all disciplines, including environmental studies and economics. There is a good amount of full text in the database.
Web of Science -- An index of over 11,000 high quality journals in the sciences, social sciences, and humanities. It has extensive coverage for environmental topics, including environmental economics. This is an index only--not a full text database--so you will need to use the Find-It button to get the full text via other methods.
LexisNexis -- Full text of news sources, including business and trade journals. This may be a good place to look to figure out alternative viewpoints on issues.
Political Science Complete -- Focuses on journals in political science; good for policy discussions.
WorldCat -- Helps you identify books, technical reports and government publications.
Databases with Environmental Studies Focus:
AgEcon Search -- An open access repository of full-text scholarly literature in agricultural and applied economics. Documents include working papers, conference papers and journal articles and are available in full text (pdf).
Environmental Policy Collection -- From the University of North Texas, this digital library collection of documents "... contains a variety of open access resources that provide a balanced view on environmental issues and their potential consequences. The current focus of the collection is climate change."
Greenfile -- covers all aspects of human impact to the environment. Its collection of scholarly, government and general-interest titles includes content on global warming, green building, pollution, sustainable agriculture, renewable energy, recycling, and more.
SciTech Connect -- Contains bibliographic records for energy and energy-related scientific and technical information from the Department of Energy (DOE) and its predecessor agencies, the Energy Research and Development Administration (ERDA) and the Atomic Energy Commission (AEC). The Database provides access to DOE publicly available citations from 1948 through the present, with continued growth through regular updates.