"Pocket Constitution" is currently the second-best-selling book on Amazon after receiving attention from Khizr Khan's Democratic National Convention speech and his subsequent feud with Donald Trump.

The portable version of the U.S. Constitution is currently sandwiched between the recently released "Harry Potter and the Cursed Child" and "Fantastic Beasts and Where to Find Them," another novel set in the "Harry Potter" universe.

Last Thursday, Khan, the father of the late Army Capt. Humayun S.M. Khan, asked Trump if he has ever read the Constitution, and then pulled out his own copy that he said the Republican nominee could borrow.

Trump responded to Khan over the weekend and implied that Khan's wife, Ghazala, who was on stage at the DNC but didn't speak, was silent because she wasn't allowed to speak as a Muslim woman, a claim which she disputed Sunday in a Washington Post op-ed.

Since then, Khan has continued to denounce Trump, including accusing him of being "a person without a soul," while Trump has continued to defend himself from what he perceives as attacks on his character.

The version of the "Pocket Constitution" that Khan employed during his speech was the ACLU's, which led the organization to starting giving away the usually $5 book for free with the coupon code POCKETRIGHTS, according to Entertainment Weekly.