Reference for Yevamot 29:8
ת"ש מעשה בבתו של רבן גמליאל שהיתה נשואה לאבא אחיו ומת בלא בנים וייבם רבן גמליאל את צרתה ותסברא רבן גמליאל מתלמידי ב"ש הוא
one of the disciples of Beth Shammai!<span class="x" onmousemove="('comment',' Obviously not. How, then, could it he assumed that he acted in accordance with a ruling of Beth Shammai? ');"><sup>22</sup></span> But [this is the explanation]: R. Gamaliel's daughter was different because she was incapable of procreation.<span class="x" onmousemove="('comment',' And the rival of such a woman is permitted to the brothers. V. Mishnah supra 2b. ');"><sup>23</sup></span> Since, however, it was stated in the final clause, 'Others say that R. Gamaliel's daughter was incapable of procreation' it may be inferred that the first Tanna is of the opinion that she was not incapable of procreation! — The difference between them<span class="x" onmousemove="('comment',' The 'Others' and the first Tanna. ');"><sup>24</sup></span>