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J.K. Rowling, John Green, Tahereh Mafi, and Malala Yousafzai are just some of the authors speaking out against Donald Trump’s controversial immigration ban.

Friday saw the president sign an executive order that not only halts refugees from entering the United States, but also immigrants from seven “Muslim-majority” countries, including Syria, Somalia, Libya, Yemen, Iraq, Sudan, and Iran. The action also initially applied to green card holders (a.k.a. permanent residents).

Following the signing, refugees flying into the United States were detained at airports all over the country, sparking protests and calls for donations to the ACLU (American Civil Liberties Union).

From the Harry Potter scribe herself, to the Nobel Peace Prize-winning Yousafzai and An Ember In the Ashes author Sabaa Tahir, here are some of the authors taking a stand against Donald Trump’s latest executive order: