intercalation so long, until the day-quarters summed up to two months. Or, on the other hand, they anticipated intercalating the year at once by two months, when they expected that at the time of the next coming intercalation circumstances would distract...
The Chronology of Ancient Nations: An English Version of the Arabic Text of ... - Page 56
by Muḥammad ibn Aḥmad Bīrūnī - 1879 - 464 pages
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