Information of the oldest teachings may be obtained by analysis of the oldest texts. One method to obtain information on the oldest core of Buddhism is to compare the oldest extant versions of the Theravadin Pali Canon and other texts.[note 27] The reliability of these sources, and the possibility to draw out a core of oldest teachings, is a matter of dispute.[page needed][page needed][page needed][page needed] According to Vetter, inconsistencies remain, and other methods must be applied to resolve those inconsistencies.[note 28]

What is in dispute regarding the research into the core of the teachings?