See the Princeton University Library's useful discussion of primary versus secondary sources.

As you work with your primary sources, keep in mind the following questions and ideas to help you evaluate these sources:

• Creator - Who created this document, and why? What is the creator's relationship to the events they are relating?

• Audience - What was the original audience for this document?

• What is Missing - What gaps are there in the document? What information does not appear? Why do you think this might be?

• Collection Context - What other materials are found around the document within the manuscript collection? How does the document fit into the story of the person, family, or organization that the collection is telling? Is the document typical or atypical of the collection?

• Historical Context - When was the document created? What else is happening during the creation of this document? How might that influence the document?

• Materiality - Think about the material nature of the document (paper, handwriting, length, size, etc.). How does this influence the way you read the document? What does it tell you about the creator and/or audience? What other evidence can you gain from the physical object that you might not find in a digital version?

As you conduct your search for secondary material, keep in mind the following questions to help you select high-quality and relevant resources:

• Evidence - What kind of secondary material do you need to support your argument?

• Audience - For whom is the resource intended?  Researchers, undergraduates, the general public?

• Discipline - Is the resource written from within a particular discipline?  For example, is the book or article meant for historians, literary scholars, art historians?  You will want to consider this question once you have found resources, but it is also a useful question to ask about your own argument.  Knowing your own approach will help you to know where to look—in which databases and so on—for secondary literature.

• Expertise - What is the author's training?  Has the book or article been reviewed by other experts in the field (i.e., has it been peer-reviewed)?

• Timeliness - When was the book or article published?  Recently published works will reflect current scholarship on a topic.

• Objectivity - Does the author present a balanced point point of view?  In other words, does the author present competing interpretations fairly or are alternative readings misrepresented in service of the author's agenda?  Does the tone seem objective or overly emotional?

• Documentation - Does the author adequately cite other literature relevant to his or her argument?  Of what quality are these citations?  (If the author includes quality secondary sources, you can use his or her bibliography to find further resources for your own project.)

See these resources for further information on evaluating secondary literature:

• Tips for Evaluating Sources (Diana Hacker)

• Evaluating Sources (Purdue Online Writing Lab)