Reference for Niddah 60:6

טימא וטיהר בזכר וטימא וטיהר בנקבה מה כשטימא וטיהר בזכר יצירתו כיוצא בו אף כשטימא וטיהר בנקבה יצירתה כיוצא בה

until the forty-eighth day.<span class="x" onmousemove="('comment',' It being assumed that the miscarriage was a male and that the thirty-fourth day was therefore still within the thirty-three clean days prescribed for a male birth, so that the second discharge on the forty-first day was the first menstrual one after the completion of the thirty-three clean days in consequence of which she must wait another seven days to complete the menstruation period. Her ritual immersion, therefore, cannot take place before (41 + 7 = 48) the forty-eighth day. ');">⁶</span>

Jastrow