The major limitation of this study was to fully access articles. Most of the good articles were limited to access though other libraries were also visited. For that reason, the review might have missed out on very essential and relevant data. Another limitation was the language of research. In this systematic literature review, one of the criteria of search being articles published in English language, excluded a lot of articles published in other languages. English language is the language which both writers can read and interpret well given the fact that there was not enough time to translate other articles. Lack of financial resource might have limited the research as well.