Reference for Yevamot 39:9
<big><strong>גמ׳</strong></big> כלל לאתויי מאי אמר רפרם בר פפא לאתויי צרת אילונית וכדרב אסי
MAY PERFORM THE <i>HALIZAH</i> OR MAY BE TAKEN IN LEVIRATE MARRIAGE.<span class="x" onmousemove="('comment',' Since the forbidden relative may never marry the levir, her sister does not come under the prohibition of 'the sister of his zekukah' i.e., of 'the woman related to him by the levirate bond'. ');"><sup>23</sup></span> PROHIBITED BY VIRTUE OF A COMMANDMENT' [REFERS TO] THE SECONDARY DEGREES IN RELATIONSHIP FORBIDDEN BY THE RULING OF THE SCRIBES. 'PROHIBITED BY VIRTUE OF HOLINESS' [REFERS TO THE FOLLOWING FORBIDDEN CATEGORIES]: A WIDOW TO A HIGH PRIEST;<span class="x" onmousemove="('comment',' Whose holy status precludes him from marrying a widow. V. Lev. XXI, 13f. ');"><sup>24</sup></span> A DIVORCED WOMAN, OR ONE THAT HAD PERFORMED <i>HALIZAH</i> TO A COMMON PRIEST;<span class="x" onmousemove="('comment',' Where his brother unlawfully married such a woman and died without issue. The levir must not marry her on account of his holy status. v. Lev. XXI, 7. ');"><sup>25</sup></span>