It is vital to critically evaluate sources before using them. Whether you are reviewing a book, a newspaper article, or any other source, consider the following:
What is the author’s background—experience, training, and reputation—in the field of study?
How credible is the publication? Who is the publisher? Is the person or organization reputable? What other publications has the author or organization published?
How reliable are the data, especially the statistical information? Generally, statistics drawn from government documents and scientific and academic journals are more reliable than those reported in the popular press (e.g., general-interest magazines).
How recent is the reference? As a rule, it is best to be familiar with the most recent source you can find, even when the topic is historical.