**17. Determining what is known from scientific literature**

When problem to be addressed are clearly defined, professionals should be knowledgeable of prior or continuing efforts toward resolving the issue. This ought to comprise a systematic method for identifying, retrieving, as well as evaluating appropriate scientific reports based on research, panels, as well as conferences associated toward the issue of interest. The best way to start this investigation is through a formal study of the official literature review. Much databases information is available toward facilitating such a review; the best known of these public/environmental health purposes remain Scirus (Elsevier), MEDLINE Ovid, PubMed, ProQuest Dissertations and theses, CINHAL EBSCO Host, Web of Knowledge, Research Gate, Scopus/Elsevier, Mendeley, Geobase/Elsevier, Environment Complete/Ebsco, Campbell Collaboration databases, Google Scholar, Google Web, SSRN, Academia etc. These subscribed databases through an institution, can selectively remain accessible in the Internet, or occasionally the public can access it from institutions (like the National Library of Medicine [110], Hinari, Universities, Research4life as well as public libraries). There are also a number of organizations that sustain Internet sites that help identify appropriate information, together with several government health departments, the World Health Organization, Centers for Disease Control and Prevention, as well as the National Institutes of Health etc. It is remarkable to note that the published literature does not cover all (Type 2) intervention studies (see **Table 1**).
