Surya Siddhanta
पुनर् द्वादशधात्मानम् व्यभजद् राशिसञ्ज्ञकम् । नक्षत्ररूपिणम् भूयः सप्तविम्शात्मकम् वशी॥
Brahmä, the self-restrained one (vaçi), again divided his mind-induced sphere into twelve parts as the räçis and still again divided it into 27 divisions as the constellation of stars (nakshatra).
english translation