“…Another 30 articles were obtained from scanning the reference lists of known primary and review articles in our personal files. After reviewing the full manuscripts of 145 articles, 36 English (3–6,11,14, 33–62), seven German (63–69), four Italian (70–73), two French (74,75), two Chinese (76,77), two Bulgarian (78,79), one Spanish (80), one Polish (81), one Turkish (82), and one Dutch (83) article were selected for inclusion in the overview. There were six articles in which the two reviewers initially disagreed on eligibility but this was resolved easily by consensus.…”