This nickname first appeared in "Dokuganryu Masamune DATE" (written by Shien TAKAHASHI, emended by Tenzui KUBO, published by Shobido: Osaka in September, 1901).
『独眼竜伊達政宗』（高橋紫燕・著，久保天随・校、大阪：鍾美堂，明34（1901）9月刊行）が出典。