While there may be more ways for entrepreneurs to spread their ideas than ever before, putting out a book is still the most effective credibility builder around. Unfortunately, getting one published is harder than ever, not to mention the difficulty in making people notice it afterward. The six literary agents profiled below have cracked the code.

1. Elyse Cheney

Early in her career, while working for the esteemed literary agency Sanford J. Greenburger Associates, Elyse Cheney discovered and sold A Heartbreaking Work of Staggering Genius by the notoriously entrepreneurial writer Dave Eggers. This would come to typify the types of projects for which Cheney would become known. She would go on to found her own agency, Cheney Literary, which has become synonymous with a certain brand of upmarket nonfiction. In bringing New York Times bestseller The Dressmaker of Khair Khana  to market, she helped shed light on the little known traumas and triumphs of female entrepreneurs in war town countries. And her titles Moonwalking With Einstein and Citizenville by California Lieutenant Governor Gavin Newson are poured over by businesspeople and bureaucrats alike.

2. B.G. Dilworth

B.G. Dilworth knows how to place a book with the right editor. He has had more than forty bestsellers, both as a Senior Agent at Author & Artists Group and as the founder of his own agency. But what really gets him excited is working with his clients on every aspect of their projects. He offers advice at each stage on book conception and organization, editorial assessment, image and brand management, co-writer selection, and rights licensing. As such, his successful titles have varied widely in terms of topic and theme--including everything from the revisionist Zodiac Killer tale The Most Dangerous Animal of All by Gary L. Stewart to RE/MAX founder Phil Harkin's Everybody Wins.

3. Mel Berger

From his storied beginnings working in the mailroom of the William Morris Talent Agency, Mel Berger has represented some of the most well known innovators, businesspeople, thinkers, politicians and celebrities of the past half-century. Now as a Partner at WME (William Morris Endeavor), Berger's roster includes everyone from water supply innovation expert Seth M. Siegel (Let There Be Water) to members of the Duck Dynasty clan. Widely renowned as a legend in his field, Berger's eye for new talent will keep him relevant well into the decades to come.

4. Kimberly Witherspoon

In an atmosphere where traditional publishing and digital media are often viewed as adversaries, Inkwell Management founding partner Kimberly Witherspoon sees nothing but opportunity. Having started her own agency at 26, Witherspoon built her business by using every tool, technology, and tactic available to her to develop and advocate on behalf of her clients. Today this includes sophisticated data analysis and online innovation. In addition to her agency's large roster of award winning and bestselling novelists, Inkwell represents famed entrepreneurs and thinkers such as Frans Johansson (author of The Medici Effect and The Click Moment), Polly Moore (author of The 90 Minute Baby Sleep Program), and George Anders (author of Merchants of Debt).

5. Stephen Hanselman

With threats to the traditional business model of publishing coming from all sides, the best agents have had to make sure to change with the times. Stephen Hanselman is one such person. His firm LevelFiveMedia, LLC represents business gurus like Tim Ferriss (The Four-Hour Work Week), Ryan Holiday (The Obstacle Is The Way, Ego Is The Enemy), and Jack Canfield (Chicken Soup For The Soul). Hanselman's ability to secure this niche has depended on his agency's policy of optimizing "authors' media opportunities, expanding their platforms, and enhancing their ability to reach and mobilize their constituencies."

6. Elizabeth Winick Rubinstein

Elizabeth Winick Rubinstein forged her path as a successful literary agent by embracing innovation in what is often a conservative industry. Her first job in publishing was at a small startup, which she played a pivotal role in transforming into into a thriving enterprise. The next phase of her career was in the then-new field of audio books. Today she is the President and senior agent at McIntosh & Otis, an almost ninety-year old firm that has represented and now administers the rights of legends such as John Steinbeck, Walker Percy, and Sinclair Lewis (whose dystopian novel It Can't Happen Here has regained popularity in light of recent political events). Under Rubinstein's stewardship the agency, the agency has diversified heavily into nonfiction and various other titles by pop culture and literary up-and-comers as part of her bid to secure the agency's stature well into the 21st Century.

7. Jim Levine

Jim Levine's interests and influences include software development, informational product design, music, and photography. It is no wonder his unorthodox literary agency, Levine Greenberg Rostan, is so well fitted to the multiplatform era. He has long held that "being an agent is a continuing liberal arts education" that gives him "an opportunity to engage with experts and thought leaders in a wide variety of fields and help shape their work to reach the broadest possible audience." The result has been an unrelenting track record of hits that include The Five Dysfunctions of Team by Patrick Lencioni, Predictably Irrational by Dan Ariely, and Youtility by Jay Baer.