.</ref> However, the Government of Japan conducted a study in 1991 that considered historical documentation from Japan, Korea, and the United States National Archives, as well as testimonies of former comfort women, military personnel, officials of Korea’s government, operators of comfort stations, residents in the areas of the comfort stations, and history researchers. The study concluded that it is impossible to establish the number of comfort women, as no document has been found which either indicates their total number or provides enough ground to make an estimate.