(Lillian Cunningham | The Washington Post)

On the list of recommended summer reads that Microsoft founder and CEO Bill Gates just posted to his personal blog, not one is a business book.

The tech titan and philanthropist spent decades building one of America's biggest corporations, which make it notable that his shared summer reading list is hardly made up of business bestsellers. Rather, it includes books on topics like vaccines (On Immunity) and carnivorous diets (Should We Eat Meat?). Other books also tackle scientific questions, from the serious and profound (The Magic of Reality) to the absurd (What If?). Gates even includes a book from the popular blogger and humorist Allie Brosh (Hyperbole and a Half).

Gates' widely watched annual book list is a reminder that while plenty of business leaders tote around their dog-eared copy of Good to Greator hand their employees the latest guru's guide to achieving instant success, some prominent figures have found more inspiration elsewhere.

Whether it's biography, history, nonfiction or spirituality, it's not uncommon (nor is it little wonder) to hear executives recommend non-business books. Jack Dorsey, one of Twitter's founders and the current CEO of Square, is known for giving all of his employees a copy of Atul Gawande's The Checklist Manifesto. Goldman Sachs CEO Lloyd Blankfein has said that he's been trying to finish Daniel Boorstin's tome The Discoverers for years and recently read Dead Wake, Erik Larson's bestseller on the Lusitania.

Years ago, I asked Costco founder Jim Sinegal what he was reading. It was the fall of 2008, in the middle of the financial crisis. Sinegal mentioned The Defining MomentJonathan Alter's book about Franklin D. Roosevelt's critical first 100 days as president, when he took over amid the darkest days of the Depression. Few books seemed more apt for leading in that moment.

Ever since then, I often ask executives to share their favorite book on leadership that isn't pulled from the crowded business book shelf. I also take note of when others recommend such books to their employees or in the press. Here are a few non-business books that leaders have recommended over the past year or so, if you're looking to add some more to your summer reading lineup:

Andresseen Horowitz co-founder Ben Horowitz recommends . . .

Horowitz told me last year that one of the most inspirational books he's read is The Black Jacobins by C.L.R. James. It's about Toussaint L'Ouverture, the leader of the most successful slave revolution in history. "He would capture English and Spanish soldiers and make them part of his army, which is amazing — as is how he thought about adopting the best parts of their culture into his culture," Horowitz told me. "If you could read one book on leadership, that would be the one I would pick."

Microsoft CEO Satya Nadella recommends . . .

In a memo to employees after becoming CEO early last year, Nadella recommended The Boys in the Boat by Daniel James Brown, about the 1936 U.S. Olympic crew team. He called it "a great story of how commitment, determination, and optimism among groups can create history." He quotes a passage from the book about what the author calls "the swing of the boat," in which the team of rowers are working in "such perfect unison that no single action by any one is out of synch with those of all the others." Nadella wrote that "as a company, as a leadership team, as individuals, that is our goal — to find our swing."

Container Store CEO Kip Tindell recommends . . .

In an interview I did with him last year, Tindell recommended I Believe in Zero by Caryl Stern, the CEO of the U.S. Fund for Unicef. While the book's author is a friend of his, Tindell said its premise — that the world has the power to reduce the number of preventable deaths of young children to zero— is the epitome of leadership. "Most limits are self-imposed," Tindell said. "That's what leadership is all about: getting somebody to see your vision and believe it's possible."

Gates Foundation CEO Sue Desmond-Hellman recommends . . .

No list like this would be complete without a biography of a former president, particularly Abraham Lincoln. (Indeed, Bill Gates included a Doris Kearns Goodwin book about Teddy Roosevelt and William Howard Taft on his summer reading list last year.) Desmond-Hellman, a former Genentech executive and former chancellor of the University of California at San Francisco, told On Leadership that Lincoln by David Herbert Donald was a favorite. "It demonstrates how Abraham Lincoln, a man from humble beginnings who had many flaws (I can relate!)," she wrote in an email, "can grow and develop into a great leader who is able to tap into the best in others and lead our country in an extraordinary way."

Former Campbell Soup CEO Doug Conant recommends . . .

Conant told me in an email that one of his favorite books is The Road Less Traveled. "This book was originally published in 1978, the year I was married. Both my wife and I read it that year and it has been in my library ever since." He wrote that while the subject of spiritual growth is often avoided by leaders, they need to embrace it to really grow. "Scott Peck's work arrived in my life at a time when I was particularly open to the pursuit of spiritual growth. And his thinking around leveraging discipline and love in pursuit of that growth was extraordinarily helpful."

Google's senior vice president of people operations Laszlo Bock recommends . . .

While hardly a new book, Bock told me in an interview that Impro by Keith Johnstone is a "fantastic leadership book," thanks in particular to a chapter about masks. The author, who teaches improvisational theater, discusses how people who struggled getting into character are transformed by simply putting on a mask. After doing so, "they had these fully formed personalities; their posture would change, their voice," Bock said of the book. "The leadership insight is that if you're stepping into a leadership role — or anything you're uncomfortable with — you have to imagine you're playing this role." Bock said he's shared the book with other people, "and they've come back and said, 'Wow, this really freed me up to make my voice heard.' "

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