Systematic reviews. Some examples.

Reviewing the literature is a scientific inquiry that needs a clear design to preclude bias. It is a real enterprise if one aims at completeness of the literature on a certain subject. Going through refereed English language journals is not enough. On line databases are helpful, but mainly as a starting point. This article gives examples of systematic reviews on vitamin C and the common cold, pyridoxine against the premenstrual syndrome, homeopathy, and physiotherapy.