Talmud for Yevamot 6:4
כֹּהֵן גָּדוֹל לֹא יִשָּׂא אַלְמָנָה, בֵּין אַלְמָנָה מִן הָאֵרוּסִין, בֵּין אַלְמָנָה מִן הַנִּשּׂוּאִין, וְלֹא יִשָּׂא אֶת הַבּוֹגֶרֶת. רַבִּי אֱלִיעֶזֶר וְרַבִּי שִׁמְעוֹן מַכְשִׁירִין בְּבוֹגֶרֶת. לֹא יִשָּׂא אֶת מֻכַּת עֵץ. אֵרֵס אֶת הָאַלְמָנָה, וְנִתְמַנָּה לִהְיוֹת כֹּהֵן גָּדוֹל, יִכְנֹס. וּמַעֲשֶׂה בִיהוֹשֻׁעַ בֶּן גַּמְלָא שֶׁקִּדֵּשׁ אֶת מָרְתָא בַת בַּיְתוֹס, וּמִנָּהוּ הַמֶּלֶךְ לִהְיוֹת כֹּהֵן גָּדוֹל, וּכְנָסָהּ. שׁוֹמֶרֶת יָבָם שֶׁנָּפְלָה לִפְנֵי כֹהֵן הֶדְיוֹט, וְנִתְמַנָּה לִהְיוֹת כֹּהֵן גָּדוֹל, אַף עַל פִּי שֶׁעָשָׂה בָהּ מַאֲמָר, הֲרֵי זֶה לֹא יִכְנֹס. כֹּהֵן גָּדוֹל שֶׁמֵּת אָחִיו, חוֹלֵץ וְלֹא מְיַבֵּם:
A high-priest may not marry a widow, both a widow from betrothal and a widow from marriage. And he may not marry a bogereth (one who has matured beyond maidenhood), [it being written (Leviticus 21:14): "And he, a woman in her virginity shall he take" — to exclude a bogereth, whose virginal signs are partially lost (in the process of maturing)] R. Eliezer and R. Shimon permit a bogereth. [The halachah is not in accordance with them.] He may not marry a mukath etz (a virgin accidentally deflowered). If he betrothed a widow and were appointed high-priest, he may marry her. It happened with Yehoshua b. Gamla that he betrothed Marta the daughter of Baitus, and the king appointed him high-priest, and he married her. If a shomereth yavam (a woman awaiting yibum), fell before a regular priest (for yibum), and he was appointed high-priest — even if he had made a ma'amar in her, he may not marry her. If the brother of a high-priest died, he gives her chalitzah, but he does not take her in yibum.