During a literature search, you must make some decisions about the information you are looking for.
1. What kind of resources are you looking for?
Information in popular periodicals such as The New York Times, Wall Street Journal?
Often articles in popular periodicals can lead you to references to the scholarly literature
Information that has been aggregated from many sources (such as a textbook)?
Even information in a recently published book may be at least 3-5 years old.
Information in scholarly journal articles?
This is the place to find the most recently published research evidence.
A PICO(T) question is usually answered by accessing the scholarly journal literature
Ready reference information: a fact, a definition, a short description, drug side effect, etc.?
2. What aspects of your topic are you interested in?
Are you interested in the historical, ethical, psychosocial, or policy aspects of the topic? Or are you looking for the clinical/biomedical aspects of the topic?
3. How much information are you looking for?
What is the scope of the project?
Do you want several recent articles on a topic?
Are you writing a paper and looking for both background information from textbooks plus some recent journal information?
Are you writing a dissertation?
What level of evidence do you require? Are you looking for evaluated, "peer-reviewed," scholarly sources? Do you want information appropriate for clinical application? Information in a journal article may not necessarily be ready for clinical application; the critical appraisal must come first.