Ketaka's Commentary on The Sign Rtags jug gi dgons grel ke ta kai gan mdzod Nag-dban-blo-bzan-legs-bsad-sgron-me, Rgyal-sras. Zi-lin : Mtsho-snon mi rigs dpe skrun khan : Mtsho-snon Zin-chen Zin-hwa dpe khan gis bkram, 1991 [i.e. 1992] 7542002724 Study on the Tibetan grammatical distinctions