GB, 1, 1, 5, 4.0 tebhyaḥ śrāntebhyas taptebhyaḥ saṃtaptebhyo daśatayān ātharvaṇān ārṣeyān niramimataikādaśān dvādaśāṃs trayodaśāṃś caturdaśān pañcadaśān ṣoḍaśānt saptadaśān aṣṭādaśān navadaśān viṃśān iti //

GB, 1, 5, 25, 4.1 dvādaśavarṣaṃ brahmacaryaṃ pṛthag vedeṣu tat smṛtam /