Total revenue at Penguin Random House inched up 1.1% in the first half of 2017, over the first six months of 2016, while earnings at the publisher rose 11.4%.

Parent company Bertlesmann reported that worldwide sales were €1.53 billion ($1.81 billion) in the period, up from €1.52 billion. Meanwhile, EBITDA (earnings before interest, taxes, depreciation, and amortization) was €206 million, up from €185 million in the first six months of 2016. Bertlesmann said the earnings improvement reflected continued benefits from the Penguin-Random House merger.

In a letter to employees, PRH CEO Markus Dohle attributed the financial improvements primarily to “the strength of print and the growth of audio sales.” These countered “the continuing general trend in lower demand for e-books.” (One area of e-book growth was at PRH’s Spanish-language division, Penguin Random House Grupo Editorial).

In terms of specific titles that lifted the publisher, Dohle pointed to bestsellers Camino Island, Into the Water, and Thirteen Reasons Why. Jay Asher’s YA novel, originally published 2007 by Razorbill, sold over 1 million copies thanks to its Netflix adaptation; the title was PRH’s top seller in the first half of the year.

Dohle also noted the strength of PRH’s backlist, which he called “the core economic engine of our company.” He added that the backlist business has been enhanced by “our data-driven approach to increasing the online visibility of our books.” In one example of the strength of the backlist, PRH sold more than 5 million copies of Dr. Seuss books in the first half of 2017.

In its announcement, Bertelsmann said book publishing remains a core business for the company. Dohle noted that in 2017 PRH bought the Spanish publisher Ediciones B and the apparel company Out of Print (which specializes in literary-themed items). The publisher, Dohle added, is “ramping up” its audio business in such countries as Canada and India. Additionally, in the first half of the year, PRH acquired global rights to two books being written by former President Barack Obama and former First Lady Michelle Obama.

Dohle said PRH has a strong list for the second half of the year, but cautioned that the publisher faces “a marketplace heavy with unrelenting new-title competition” and “a crowded media landscape with constantly breaking news and attention-grabbing headlines.” Because of this, he went on, “it is all the more essential for us to be laser-focused—on every sale, every title marketing and publicity plan, every innovative idea, and every readercentric initiative.”