It is important to properly acknowledge all sources consulted for dissertation. When using viewpoints of authors to support your own arguments you must acknowledge such sources in your text
You should be honest and not pass off another person’s work as your own. If you do this, you are committing plagiarism, a serious academic offence that can lead to the rejection of your dissertation/thesis.
For more info: VUT Postgraduate Referencing Guidelines: bibliographical referencing for theses, dissertations, and projects reports.