Sentence examples for relevant studies were contacted from inspiring English sources

The reference lists of the included papers were examined for further papers, and the authors of the most relevant studies were contacted requesting details of any other studies which they thought were important in the area.

Authors of relevant studies were contacted for missing data.

Authors of relevant studies were contacted, where possible, for data that could not be extracted from the published articles.

Bibliographies of potentially eligible full-text publications were also searched and when necessary, authors of relevant studies were contacted for clarification and for additional information.

Where necessary, the relevant authors of these studies were contacted to obtain further data.

The investigators of the original studies were contacted if relevant information on eligibility or key study data were not available in the published report.

Authors of the eligible studies were contacted for additional data relevant to this meta-analysis, as necessary.

Bibliographies from relevant studies were reviewed, and authors of potentially eligible studies were contacted when necessary to request further information regarding study design or primary outcomes.

Authors of studies were contacted when results were unclear or when relevant data were not reported.

References from relevant studies were examined for additional citations, and experts and authors of pertinent studies were contacted for any further references.

The authors of the included studies were contacted to give more information about their studies and other possibly relevant ones.