'Phags-pa script
From 1977 onwards, the focus of Junast's research turned to the study of documents and monuments written in the 'Phags-pa script, with his first publication on the subject being a collection of Yuan dynasty official seals carved in the convoluted "seal script" form of the 'Phags-pa script. During the 1980s he published numerous articles on the 'Phags-pa script, culminating in a critical edition of the Yuan dynasty rhyming dictionary of Chinese in the 'Phags-pa script, "Menggu Ziyun".