If your University textbook doesn't have headings and subheadings, you should create them yourself.
Anytime there is a line break, an extra line between two blocks of text, a new subject is usually being introduced.
For every block of text, identify the subject by the number of sentences that refer to the subject, usually a noun, i.e World War I. This noun may be qualified by adjectives, such as “the start” or “life during” or similar and some statement about it's importance, such as “poverty grew" or “people rationed food."
These can be considered subheadings.
Headings are usually created for a series of subheading sections where the topic relates to the same subject.
Anyone can find topics by highlighting frequently used nouns–person's, places, or things about which most of the writing is about.