Reference for Yevamot 74:11

ספק ויבם שבאו לחלוק בנכסי מיתנא

If the 'doubtful son'<span class="x" onmousemove="('comment',' A son of whom it is not known whether he was a nine-months child of the deceased, or a seven-months one of the levir. (V. our Mishnah). ');">²⁰</span> and the levir came to claim a share<span class="x" onmousemove="('comment',' Lit., 'to divide', or 'to dispute'. ');">²¹</span>

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