A $1 pocket version of the U.S. Constitution reached the best-seller book list on Amazon Saturday afternoon.

The increase in sales happened after Khizr Khan spoke last Thursday at the Democratic National Convention about his son, Capt. Humayun Khan, who died in Iraq in 2004.

“If it was up to Donald Trump, he never would have been in America,” he said, a Muslim-American lawyer born in Pakistan. During his speech, he also brandished a pocket Constitution, offering to lend it to Donald Trump. “Have you even read the United States Constitution?” he asked. “Look for the words ‘liberty’ and ‘equal protection of law.’”

Shortly afterward, sales and searches for the pocket Constitution showed a sharp rise.

At 11 a.m. EDT Sunday, a 52-page pocket Constitution published by the National Center for Constitutional Studies was #2 on the best-seller book list on Amazon. On Thursday, Google Trend data showed a sharp rise in the number of searches for the term “pocket constitution” in the U.S. after Khan’s speech. Google searches for the term also showed a spike on Friday and Sunday morning.

At ConstitutionBooklet.com, a pocket Constitution is available to print, along with a video tutorial on how to fold it into a pocket-sized document.

The ACLU is selling pocket Constitutions for free, including shipping, with the offer code POCKETRIGHTS through Nov. 8. People can also buy a pocket Constitution online from the National Constitution Center for $2.50, or from Oak Hill Publishing Company for $3.95.

Amazon did not immediately respond to an email request for comment.