INFORMATION SOURCE AND SEARCH STRATEGY.
Data and information for the purposes of this paper review were obtained through an internet based literature search using the english key terms combination as illustrated in appendix X. The search has covered all articles published in peer reviewed journals in english if available since 1945 to the present day. The search used mainly the databases Cinanl, PubMed, Psyinfo, Cochrane Library, Google Scholar, Embase , ScienceDirect, and Scopus,. The World Health Organisation, United States National Health Institute Centre for Diseases Control, Clinical Trials gov and ISRCTN registry web sites were also utilised . In addition links from the original websites and articles references were searched .