When you do research, whether it is for an argumentative paper, a research paper, or any such endeavor, you should think about the types of sources you are using. Sources, or the books, article, websites, encyclopaedia (etc) from which you learn information can be classified into three categories: primary, secondary, or tertiary.
Primary sources are composed by someone who was around at the time of an event and has first-hand experience with it. Primary sources include interviews, autobiographies, works of art, photographs, drawings, and historical records like marriage licenses or pieces of legislation.
Secondary sources draw on primary sources (as well as other secondary sources) to further a particular thesis, or point of view. For college research, you should utilize articles that are written and reviewed by experts in a particular field. Experts use secondary sources, articles published in journals and books, to communicate with one another and further the exploration of a given idea or topic.
Tertiary sources collect and contextualize information created by others, but often do not provide their own opinions on a topic. Tertiary sources are sometimes also called 'reference books' or 'reference materials'. This includes encyclopaedia, dictionaries, and thesauri. The entries in these sources are generally short and objective.