 In addition, a single page from a different copy of the same edition of the "Pearl in the Palm" was found at the Northern Mogao Caves in 1989.The book transcribes the pronunciation of Chinese words into Tangut characters, and the pronunciation of Tangut characters into Chinese characters, and so is a very important source for Tangut historical phonology, and was the primary source before the publication of monolingual Tangut dictionaries.In 1909, the Russian explorer Pyotr Kozlov unearthed a number of texts and artefacts in Ejin Banner, Inner Mongolia, including the "Pearl in the Palm" and transported them back to St. Petersburg, Russia.