DK is a book publishing company

DK Inc. began publishing in the United States in 1991. That same year, Microsoft bought a 26 percent stake in DK.

In 1999 they were bought by Penguin.

In 2017 Obama made a record setting book deal with Penguin Random House.

https://en.wikipedia.org/wiki/DK_(publisher)

https://www.businessinsider.com/obama-book-deal-2017-2

that was acquired by Penguin Random House