Cyrillic script consonants from the older Glagolitic alphabet for sounds not found in Greek. Tradition holds that Cyrillic and Glagolitic were formalized either by Saints Cyril and Methodius who brought Christianity to the southern Slavs, or by their disciples. Paul Cubberley posits that although Cyril may have codified and expanded Glagolitic, it was his students in the First Bulgarian Empire under Tsar Simeon the Great that developed Cyrillic from the Greek letters in the 890s as a more suitable script for church books. Later Cyrillic spread among other Slavic peoples, as well as among non-Slavic Vlachs. Cyrillic and Glagolitic were used for
Korean mixed script interjections, exclamations and onomatopoeia in "hangul". Despite the promotion of the mixed script at the end of the Joseon Dynasty, examples of Korean mixed-script writing date back to the time King Sejong's proclamation of "hangul", which was written completely in literary Chinese, with a few "idu" passages and mixed-script passages that help 'ease' the reader into the new alphabet. The first novel in "hangul", "Yongbieocheonga" (龍飛御天歌, 용비어천가) or "Songs of the Dragons Flying to Heaven", commissioned by Sejong shortly after the proclamation of the Korean alphabet. Yi Yulgok (李栗谷, 이율곡), a Korean scholar and mathematician translated the Analects of Confucius