Donald Trump’s campaign used its own funds to buy more copies of one of his books than the rest of the world did in the second week of May. The purchase was so large that it even it pushed the 2015 title onto the bestseller list of Nielsen BookScan, according to data obtained by The Daily Beast.

On May 10, the Trump campaign spent $55,000 at a New York Barnes & Noble on 3,964 copies of Crippled America: How to Make America Great Again, The Daily Beast reported Wednesday. The buy was a departure from standard campaign practice, which dictates that bulk orders be placed with the book publisher to avoid artificially boosting sales.

In the same week, other cities in the United States purchased a mere fraction of what the Trump campaign did: Seventy copies were sold in Philadelphia, 78 in Los Angeles, and 41 in Dallas.

If Trump personally profited from the book royalties, he would have violated federal law prohibiting campaign funds from being converted for personal use.

The Trump campaign did not respond on the record to inquiries about this matter. Trump’s publisher Simon & Schuster and Barnes & Noble did not respond to repeated requests for comment.

— Olivia Nuzzi and Ben Collins