The ISTC has recorded 29,777 editions to date, although some of the records included in that number are actually 16th-century works that were included in previous incunable catalogs in error, so the number of true incunabula recorded is 27,460. The number of extant incunabula is estimated to be approximately 28,000 editions, which puts ISTC extraordinarily close to completing its goal of total coverage. Documenting these last few hundred editions is a tremendous undertaking, as the works are scattered in unknown locations in many countries, leaving bibliographers with no organized way to search for them except to "look everywhere".