Biographical encyclopedia of 20th-century world leaders Biographical Encyclopedia of 20th-Century World Leaders Biographical Encyclopedia of 20th-Centrury World Leaders 并列题名：Biographical Encyclopedia of 20th-Century World Leaders The Encyclopedia of 20th-Century Athletes The Encyclopedia of 20th Century Athletes Encyclopedia of 20th century air warfare 并列题名：Encyclopedia of 20th century air warfare Practical encyclopedia of watercolor First encyclopedia of our world /