Cairo Genizah : Calendrical 

Cairo Genizah

<p style='text-align: justify;'>Calendrical work listing rhymed calendrical mnemonics, and giving remainders for groups of months and groups of 19-year cycles. The calendar describes lunar and solar months as they are counted by ‘another nation’ (lunar months of 28 days and solar months of 30 days with five intercalary days) and explains that Jewish lunar months must always occur within the same Zodiac sign.</p>