Mishnah Negaim 3:5: Hairless patches are made impure after two weeks or through two signs: thin yellow hair or expansion. Regarding thin yellow hair, [it is made impure] initially, at the end of the first week [of quarantine], at the end of the second week [or] after the exemption. And regarding expansion, at the end of the first week, at the end of the second week [or] after the exemption. And they are made impure after two weeks, which are [actually] thirteen days.

הַנְּתָקִין מִטַּמְּאִין בִּשְׁנֵי שָׁבוּעוֹת, בִּשְׁנֵי סִימָנִין, בְּשֵׂעָר צָהֹב דַּק וּבְפִסְיוֹן. בְּשֵׂעָר צָהֹב דַּק, בַּתְּחִלָּה, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. וּבְפִסְיוֹן, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. וּמִטַּמְּאִין בִּשְׁנֵי שָׁבוּעוֹת, שֶׁהֵן שְׁלשָׁה עָשָׂר יוֹם:

Mishnah Negaim 3:6: Posterior baldness or frontal baldness are made impure after two weeks or through two signs: a healed patch [of skin], or expansion. Regarding a healed patch, [it is made impure] initially, after the first week [of quarantine], after the second week [or] after the exemption. And regarding expansion, after the first week, after the second week, [or] after the exemption. And they are made impure after two weeks [maximum], which are [actually] thirteen days.

הַקָּרַחַת וְהַגַּבַּחַת מִטַּמְּאוֹת בִּשְׁנֵי שָׁבוּעוֹת, וּבִשְׁנֵי סִימָנִין, בְּמִחְיָה וּבְפִשְׂיוֹן. בְּמִחְיָה, בַּתְּחִלָּה, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, לְאַחַר הַפְּטוּר. וּבְפִסְיוֹן, בְּסוֹף שָׁבוּעַ רִאשׁוֹן, בְּסוֹף שָׁבוּעַ שֵׁנִי, וּלְאַחַר הַפְּטוּר. וּמִטַּמְּאוֹת בִּשְׁנֵי שָׁבוּעוֹת, שֶׁהֵן שְׁלשָׁה עָשָׂר יוֹם: