You cannot consider this question without knowing your research goals:
Do you have a focused research question or questions?
Have you completed a mind map or concept map?
Do you have an outline forming?
Keep these in focus when you're looking at the source. You likely won't want to spend time evaluating sources that won't contribute to your research project at all.
Information Interrogation: What?
Ask yourself: What information is included?
Look at how well the source covers your topic and the source's relevance to your research needs.
How does this particular source answer your specific research questions?
Where does the information fit logically into your outline?
Does this source cover a lot of territory (comprehensive coverage) or does it fit in nicely with a specific point in my outline? What parts of my research needs aren't being met by this source? What else do I need to discover?
What time period does the source cover? Does it need to be supplemented with more historical or more recent information?
What is the geographic coverage of the source? Look to see where it was published and if the source offers a local, regional, national, or international coverage of your topic.
What makes this source special or unique? How is information presented in this source better than information provided in other sources?
Is the source written at an appropriate academic level?
Considerations based on format:
Locate reviews of the book. A well-written review will discuss the focus of the book.
If you have the book in front of you:
Examine the table of contents: Is there are entire chapter or section on your topic?
Examine the book’s index: Are there relevant passages that reflect your research question or key terms?
If you don't have the actual book in front of you, what additional information can you locate about the book?
Locate a summary, table of contents, or index for the book:
Amazon may have a short summary or even offer a "look inside" the book.
Google Books may also allow you to view portions of the book.
A library catalog may include a summary and table of contents. Examine the catalog record for this type of information, or see if there is an image of the cover of the book. If so, this information may be located there.
Is there an abstract? Read this summary to determine if the article will add value to your research.
No abstract? Skim the article looking for relevant keywords.
What is the focus of the article? Does it cover the topic adequately or do you need additional resources to fill in the gaps?
Does the article provide sources / references that may lead to additional useful information?
What is the focus of the website? Does it offer information not available in other, more reliable resources, or does it simply repeat information available in more reliable resources?
How deep are you in the website? If you explore other portions of the website, are there other pages that offer relevant information?