When choosing sources, make sure that they are reliable. You will know if they are reliable when complete information is given. For example, when you make your academic research, you would want to find sources in scholarly works and articles published in known academic journals instead of relying in Wikipedia. In Wikipedia, you know it's unreliable because anyone could edit the information. However, academic articles provide names of authors with their affiliate institutions. Moreover, complete data is given and their references are cited well.