RULE 43

Expert testimony comes from people who are qualified by training or experience to serve as authorities on a subject. As you review your research notes, you will probably discover statements by experts offering opinions, information, or simply interesting quotations. When you cite experts in your speeches, you are calling on them as qualified witnesses to support your case. Using expert testimony allows you to borrow their credibility to make your own message more convincing. Expert testimony is especially important when your topic is innovative, unfamiliar, highly technical, or controversial.
When you use expert testimony, remember that competence is area- specific. That means that your experts can speak as experts only within their area of expertise. For example, emergency room physicians who can provide expert testimony on the physical effects of gunshot wounds may not qualify as experts on gun control legislation. As you introduce expert testimony in your speeches, be sure to present the credentials of your experts. Emphasize the recency of their statements, and, when appropriate, indicate that their words appeared in a prestigious journal, book, or newspaper.

Students from most public high schools, where it is a capital offense to put even a light pencil mark in a textbook, may have a tough time with this. However, universities require students to purchase their own books, and usually at high prices. Since you own these expensive texts, it totally acceptable and certainly advisable to write in them.
Highlighting is a good way to filter out minor details, and it’s an excellent way to review for exams. If you don’t write in your texts because you want to keep them in pristine condition, you’re making studying much more difficult than it need be. Besides, the resale value of marked-up books is exactly the same as clean books.