Reference for Yevamot 83:1

לאחר ג' אין צריכה להמתין ג' חדשים

If [the <i>halizah</i> was performed] after the three months, she need not wait three months.<span class="x" onmousemove="('comment',' From the date of the halizah. ');">¹</span> Thus it may be inferred that the three months spoken of are [to be dated] from the time of the husband's death and not from the time of the levir's <i>halizah</i>.

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