Citators are special secondary legal resources that allow users to track case or statute histories, as well as how the courts have subsequently treated cases or statutes. Citators enable users to confirm whether or not a given case or statute is still good law, as well as allowing users to find other similar cases or statutes, inculding secondary materials, that cited a given case or statute. Examples are LexisNexis's Shepard's Citations (the original source of the term "Shepardizing", which now refers to the legal citation process generally) and Westlaw's KeyCite.