Indian Chronology (Solar, Lunar and Planetary): A Practical Guide to the Interpretation and Verification of Tithis, Nakshatras, Horoscopes and other Indian Time-records, B.C. 1 to A.D. 2000 c19.10

For clearness' sake, we will present these three rules under three aspects, one of which, when we are in doubt, every problem before us must assume.