The goal of a systematic review is to identify relevant studies completely and unbiasedly [70] . It has been demonstrated [71, 72] that significant amounts of evidence would potentially be missed if the search is limited to English-only sources. Because a considerable number of clinical trials on CHM were published only in the Chinese language journals, so a comprehensive search of Chinese databases is essential for a systematic review of CHM. However, we were disappointed to find that almost twenty percent of reviews did not search any Chinese database in our study. One study [73] compared four Chinese databases and concluded that CBM is the preferred database for systematic reviewers to retrieve relevant Chinese studies, while CNKI is recommended for non-Chinese-speaking researchers due to its free searched English version website (www.global.cnki.net) and ''Cross-Language Search'' functions. CBM has no English website and a fee is charged for searching, now many Chinese medical universities have got the permission to search CBM, so maybe the most costand time-efficient way to search it is to enhance collaboration with Chinese researchers.