Registration of clinical trials: a step forward but still a long path ahead.
D002986:Clinical Trials as Topic / Q000592:standards* / Q000639:trends*; D006801:Humans; D007390:International Agencies / Q000592:standards / Q000639:trends; D020407:Internet / Q000639:trends; D010506:Periodicals as Topic / Q000592:standards / Q000639:trends; D012042:Registries / Q000592:standards*