Related for Megillah 3:4
רֹאשׁ חֹדֶשׁ אֲדָר שֶׁחָל לִהְיוֹת בְּשַׁבָּת, קוֹרִין בְּפָרָשַׁת שְׁקָלִים (שמות ל). חָל לִהְיוֹת בְּתוֹךְ הַשַּׁבָּת, מַקְדִּימִין לְשֶׁעָבַר וּמַפְסִיקִין לְשַׁבָּת אַחֶרֶת. בַּשְּׁנִיָּה, זָכוֹר (דברים כה). בַּשְּׁלִישִׁית, פָּרָה אֲדֻמָּה (במדבר יט). בָּרְבִיעִית, הַחֹדֶשׁ הַזֶּה לָכֶם (שמות יב). בָּחֲמִישִׁית, חוֹזְרִין לִכְסִדְרָן. לַכֹּל מַפְסִיקִין, בְּרָאשֵׁי חֳדָשִׁים, בַּחֲנֻכָּה וּבְפוּרִים, בַּתַּעֲנִיּוֹת וּבַמַּעֲמָדוֹת וּבְיוֹם הַכִּפּוּרִים:
If Rosh Chodesh Adar falls on Shabbath, we read (maftir) in the section of shekalim [(Exodus 30:11-16) to apprise them to bring their shekalim in Adar so that offerings may be brought from the new donations on the first of Nissan.] If it falls out during the week, it is read on the preceding (Shabbath), [even if Rosh Chodesh Adar falls out on Sabbath eve.] And we break off until the next Shabbath. [i.e., we do not read the second section ("Zachor") so that it be read on the Shabbath preceding Purim, to link the erasing of Amalek with the erasing of Haman.] On the second (Sabbath), "Zachor" (Deuteronomy 25:17-19). On the third, parah adumah (the red heifer) (Numbers 19) [to exhort Israel to cleanse themselves in order to bring their Pesach offerings in cleanliness. Which is the third Sabbath? The Sabbath after Purim. And when Rosh Chodesh Nissan falls out on Shabbath, the third Shabbath is the one before Rosh Chodesh Nissan. (It is read) in order to link the exhortation to cleansing oneself from dead-body uncleanliness to the Pesach offerings.] On the fourth, (Exodus 12:1-20): "This month is unto you" [containing the section on Pesach]. On the fifth, the usual order (of haftaroth) is reverted to. [For until then, the haftarah is of the nature of the four sections, viz. "shekalim" — (I Kings 12:1); "Zachor" — (I Samuel 15:2); "Parah" — (Ezekiel 36:25); "This month" — (Ezekiel 45:18). And from that time on, the haftarah, again, is of the nature of the section of the day.] For all (of the following) we break off [i.e., We do not read a haftarah which is of the nature of the section, but one which is of the nature of the day]: Rosh Chodesh, Channukah, Purim, fasts and ma'amadoth, and Yom Kippur.