Tibetan colophons are not only a very intriguing and peculiar literary subject to study, but also significant historical sources to develop. This article has a threefold purpose: to present colophons as sources, to provide a detailed description of the surviving Brag dkar rta so works, and to give examples of translation. Extracting information from colophons, it is possible to have a most accurate picture of lha btsun Rinchen rnam rgyal entourage, and the progress of the work at Brag dkar rta so, a well-known monastery founded by lha btsun, one of the closest disciples of gTsang smyon Heruka.