On the Ahargaṇa, or the Resolution of Years into Months, According to Special Rules which are Adopted in the Calendars for Certain Dates or Moments of Time

Not all the eras which in the calendars are resolved into days have epochs falling at such moments of time when just an adhimâsa or ûnarâtra happens to be complete. Therefore the authors of the calendars require for the calculation of adhimâsa and ûnarâtra certain numbers which either must be added or subtracted if the calculation is to proceed in good order. We shall communicate to the reader whatever of these rules we happened to learn by the study of their calendars or astronomical handbooks.

Method of ahargaṇa as applied to special dates.