To understand the secondary literature, we must first understand the literature and the primary literature.

Look at the definition of literature first.

Literature is a carrier to record human knowledge by means of words, figures, symbols, audio and video, and it can also be understood as knowledge solidified on a certain material carrier. It can also be understood as the floorboard of all social historical materials in ancient and modern times. Now it is usually understood as the sum of books, periodicals and other publications.

Look at the definition of literature again.

Primary literature: refers to the original literature with certain inventions and new ideas based on the author's own work experience, observation or actual research results, such as periodical papers, research reports, patent specifications, conference papers, dissertations and technical standards.

Finally, look at the definition of secondary literature.

The secondary literature is the product of processing and sorting the primary literature, and it is a form of literature, such as catalogues and abstract magazines (including short retrieval publications). It records the external characteristics of the chaotic primary literature, or compresses its content into a brief introduction, abstract or abstract, and forms it in an orderly manner according to a certain discipline or specialty.

It can be seen that it is the second kind of literature to select the required books from a large number of chaotic books and form a required reading list for college students.