Most books, articles and other information sources are considered to be secondary sources. However, it depends on the purpose of your research! If you are writing about racism and sexism in America, Maya Angelou's I Know Why the Caged Bird Sings, is considered a primary source because it is a first-hand account of her experiences with these issues.
If you are writing a research paper about the Civil Rights movement, it would be a secondary source because that is not a central theme in this book, although it is peripherally related. Learn more on the Selecting Sources page in this guide.
Image from Marcia J. Bates, Professor Emerita, Information Studies, UCLA