After coming off its most successful year ever, Dover Publications is getting ready to celebrate its 75th anniversary.

In addition to marking a major milestone in longevity, this has been a transitional period for the press, which has been known as a reprint house since its founding in 1941. Its titles cover the gamut from crafting to philosophy and religion and engineering. The company became part of R.R. Donnelley in June 2015 when the printing giant bought Dover parent company Courier Corp., which had owned Dover since 2000.

One of the keys to the record year has been the boom in sales of adult coloring books. Dover has published adult coloring books since the 1970s. Three Dover coloring books were among PW’s top 10 sellers in the category last year. Marjorie Sarnat’s Creative Cats Coloring Book, which sold 182, 956 units over the first 11 months of 2015, was at #3, followed by Alberta Hutchinson’s Mystical Mandela Coloring Book at #5 with 106,886 units, and Marty Noble’s Art Nouveau Animal Designs Coloring Book at #9 with 98,175 units.

Recently Dover has begun branching out and has begun publishing some titles not in the public domain and some original titles, particularly in comics and graphic novels. In January, Dover launched a line of new math books, Aurora Math Originals, beginning with Numbers by Albrecht Beutelspracher, which was translated by Andrea Bruder. Four more Aurora titles are slated to be published during the first seven months of 2016.

During the 75-day run up to its birthday, which began March 2, Dover is inviting people to share stories about their favorite Dover titles on a section of the company’s website. Those who do so have an opportunity to win free books.

The inspiration for gathering stories, publicist Beth Parker explained, came from the many thank-you letters the press has received from luminaries, including Eleanor Roosevelt, Albert Einstein, and Alexander Calder. More recently, President Barack Obama and sent a note to the press.

On May 18, Dover’s official anniversary, the press will donate 3% of the consumer sales generated through this promotion to Reading Is Fundamental.