In academic writing, you must cite the sources you use. Failure to do so constitutes plagiarism, a serious academic offence (see below).
Citations let the reader know that certain words or ideas in your work came from another source, giving credit where it's due. They allow readers to identify, find, and consult the sources themselves. In addition, citing your sources demonstrates to your instructor that your paper is based on solid (or not-so-solid) research.
Usually, your instructors will specify in class or in a course syllabus which citation style they want you to use in your papers. In addictions counselling, you will most likely be using APA style, which is defined by the Publication Manual of the American Psychological Association. The following resources provide examples of citations in APA style: