משנה אויף שמות 30:11

If Rosh Hodesh Adar falls on Shabbat the portion of shekalim is read [on that day]. If it falls in the middle of the week, it is read on the Shabbat before, and on the next Shabbat there is a break. On the second [of the special Shabbatot] they read “Zakhor;” On the third the portion of the red heifer; On the fourth “This month shall be for you;” On the fifth the regular order is resumed. They interrupt [the regular order] for anything: for Rosh Hodesh, for Hanukkah, for Purim, for fasts, for Ma’amadot, and for Yom HaKippurim.