Specify the nature of your topic. Narrow the geography and timeline of your topic, for example. Focus the general topic regarding "the effects global warming," for example, to the effects of global warming in Midwestern states over the previous ten years. Make your topic as specific as possible to help you quickly weed out unnecessary search results.
Limit your searches to different library categories. Browse hard copy or Internet library article databases related to Earth Science reading materials, for example. Search only reading materials centered on medicine or animal health, for example, to search the health effects of global warming humans and animals. Ask your librarian for help in browsing different library catalogs or search engines one at a time.
Generate a list of keywords. Write down related words to your search topic. Add words or phrases like the "ozone layer," "environmental destruction," "air pollution," "Midwestern temperatures" or "climate change," for example. Keywords will help you identify a variety of articles, books, essays and journal entries devoted to your topic.