There are many accepted citation styles.
Most journals have their own defined citation style.
If you discuss one study for one of more paragraphs, do not cite it every sentence. Introduce the study at the beginning, then end with a final citation. When this text citation style is used, references are treated like end notes and may be combined with other references or with comments in an end note. For papers with 1-3 authors list all the authors. For emailed assignments, if you can t attach a formatted file - don't worry about italicizing or underlining.