References

RPSudh, 1, 18.2
  kṣatriyo vaiśyaśūdrau ca caturṇāṃ jāyate khalu //Context
RPSudh, 7, 22.2
  syurbrāhmaṇakṣatriyavaiśyaśūdrāste jātayo vai kramaśaśca varṇāḥ //Context