Look at cited reference lists and bibliographies found at the end of research articles and books.
Unfortunately there is no easy checklist to consult to see if a source is credible or reliable. As with all information resources, the usefulness of the information may depend on what was needed in the first place.
Consider asking yourself some of these questions when evaluating a source:
Is the author clearly identified? What are his or her credentials for writing on this topic?
Is the author affiliated with an organization? What is the reputation of that organization?
Is there a link back to the organization's page or some other way to contact the organization and/or verify its credibility? (address, phone number, e-mail address?)
For websites: who publishes and/or is responsible for the website itself? Who has registered the URL?
Purpose & Audience
Are the purpose and objectives of the page clear?
Is it geared to a particular audience, or level of expertise, or geographic region, or period of time?
Is the primary purpose to provide information? to sell a product? to make a political point? to have fun? to parody a person or organization or idea?
Is it a comprehensive resource or does it focus on a narrow range of information? Is it clear about this focus?
If it is an information database, are the dates of coverage clear and appropriate to your needs? Is it easy to search? Does it present information in a usable format?
Is the page part of an edited or peer-reviewed publication?
Does the content of the page convey the amount, depth, and significance of the evidence being presented? Are the arguments persuasive?
Can factual information be verified through footnotes or bibliographies to other credible sources?
Did you find this source using an internet search engine such as Google or Bing? They neither select the best pages nor filter out questionable ones, so you need to evaluate the choices carefully.
Based on what you already know about the subject (or have checked from other sources), does this information seem credible?
Are there obvious typos or misspelled words or other signs of sloppiness?
Is it clear when the information was published and when was it last updated??
When was the research conducted?
Is this the most recent version?
For websites, are the pages current?
If there are links to other websites, are they current?
Integrity of the Data
Is the source of any factual information clearly stated?
Are the source, scope and date of any statistics clearly labeled?
Is it clear whether or not the information as been excerpted from a larger piece?
Is there a way to tell if this is the most recent version of a particular piece?
Does the author rely on photographic images to make a point? If so, be aware that digital images can be easily manipulated.
Objectivity, Bias or Point of View
Does the page display a particular bias or perspective? Is it clear and forthcoming about its view of the subject? Does it use inflammatory or provocative language?
If the page contains advertising, are the ads clearly distinguishable from the content?
Is any conflict of interest discernable between content and advertising?
As with many information sources not everything in Wikipedia is accurate, comprehensive, or unbiased. But some of its countless editors produced an article describing ways to use this free, open source encyclopedia as a research tool, including an overview of its strengths and weaknesses, as well as ways to judge article quality.