Either in quantitative research or in qualitative research, using the literature is critical. It is conducted to generate a picture of what is known and not known about a particular situation. Searching and reviewing of the relevant literature of the study could be conducted before, during, and after the data collection and analysis of the study. In qualitative research particularly the purpose conducting the literature review varies, based on the type of study to be conducted. In general, to keep the scientific nature of data, using the extensive literature should be conducted after the study has been conducted.