《史记·八书·天官书》
自月食开始的日子算起，每隔五个月一次的月食连续发生六次，每隔六个月一次的月食连续发生五次，重又每隔五个月发生一次，连续食六次，隔六个月一次的月食发生一次，每隔五个月一次的月食发生五次，总计凡经一百一十三个月上述月食的过程重复发生一遍。
月食始日，五月者六，六月者五，五月复六，六月者一，而五月者五，凡百一十三月而复始。
Starting from the day of lunar eclipse, lunar eclipse occurs six times at an interval of five months, five times at an interval of six months, once more six times at an interval of five months, once at an interval of six months, lunar eclipse five times at an interval of five months. The whole process of the above lunar eclipse repeats for one hundred thirteen months in total.