From Internet Censorship Explorer:
The Search Monitor Project: China focuses on assessing the level of transparency with regard to the self-censorship practices of search engine companies as well as the mechanisms and effects of this political censorship. (For background information, see this and this.) The following is a step by step process of a search for “human rights” (人权).
The first step is to retrieve a result set from the (uncensored) Chinese version of Google. Each result is parsed to its domain name (http://www.hrw.org/chinese/ becomes “www.hrw.org”).
The second step is to use the “site:” modifier to restrict results to the domain. The censored versions of Google and Microsoft can be queried directly, but Yahoo and Baidu must be queried from inside China because they are hosted inside China. This is because the bi-direction filtering of China’s “Great Firewall” (GFW) will block the inbound connection due to the presence of “www.hrw.org” in the search query. Conversely, search from inside China to Google to Microsoft will be blocked because of the GFW but since we are interested in search engine censorship it is necessary for us to remove the effects for the GFW.