Reference for Gittin 3:1
כָּל גֵּט שֶׁנִּכְתַּב שֶׁלֹּא לְשׁוּם אִשָּׁה, פָּסוּל. כֵּיצַד. הָיָה עוֹבֵר בַּשּׁוּק וְשָׁמַע קוֹל סוֹפְרִים מַקְרִין, אִישׁ פְּלוֹנִי מְגָרֵשׁ אֶת פְּלוֹנִית מִמָּקוֹם פְּלוֹנִי, וְאָמַר, זֶה שְּׁמִי וְזֶה שֵּׁם אִשְׁתִּי, פָּסוּל לְגָרֵשׁ בּוֹ. יָתֵר מִכֵּן, כָּתַב לְגָרֵשׁ בּוֹ אֶת אִשְׁתּוֹ וְנִמְלַךְ, מְצָאוֹ בֶן עִירוֹ וְאָמַר לוֹ, שְׁמִי כִשְׁמֶךָ וְשֵׁם אִשְׁתִּי כְשֵׁם אִשְׁתֶּךָ, פָּסוּל לְגָרֵשׁ בּוֹ. יָתֵר מִכֵּן, הָיוּ לוֹ שְׁתֵּי נָשִׁים וּשְׁמוֹתֵיהֶן שָׁווֹת, כָּתַב לְגָרֵשׁ בּוֹ אֶת הַגְּדוֹלָה, לֹא יְגָרֵשׁ בּוֹ אֶת הַקְּטַנָּה. יָתֵר מִכֵּן, אָמַר לַלַּבְלָר, כְּתֹב לְאֵיזוֹ שֶׁאֶרְצֶה אֲגָרֵשׁ, פָּסוּל לְגָרֵשׁ בּוֹ:
Every get which was not written specifically for that woman is invalid. How so? If he were passing through the market and heard the voices of scribes calling [to their apprentices: When someone comes for a get, write it thus:] "This and this man divorces this and this woman, from this and this place," and he said: "That is my name, and that is the name of my wife," it is invalid as a divorce. Even more: If he wrote it to divorce his wife therewith [i.e., not only is a get not written for divorce but for practice invalid; but even one written for the sake of divorce], if he changed his mind, and one of his townsmen found it, and said: "My name is the same as yours, and my wife's name, the same as your wife's name," it is invalid as a divorce. Even more, if he had two wives with the same name, and he wrote it to divorce the elder, he may not divorce the younger with it. [Not only is it invalid if it were not written for the sake of divorce of this man, but even if one had two wives, in which instance it was written for the sake of divorce of this man, it is invalid, since it was not written for the sake of divorce of this particular woman. (elder, younger:) not necessarily.] Even more, if he said to the scribe: "Write it for me to divorce whichever wife I choose," it is invalid as a divorce. [We are hereby apprised that we do not say that it is established retroactively that when he wrote it, too, it was this wife that he intended, so that there is (a bona fide) divorce vis-à-vis both him and her.]