Ah, final exams. It is the best of times, it is the worst of times—mostly the latter. And for students too freaked about flunking to be sure those famous lines were cribbed from Charles Dickens's A Tale of Two Cities, grabbing for the Cliffs Notes version may seem the only solution.

When Clifton Hillegass published his first study guide 40 years ago, he could hardly have foreseen the extent to which students would come to depend on his yellow-and-black striped booklets. By now hundreds of millions of them have found their way to students of every stripe, though many in academe, like Brigham Young University bookstore manager Linda Brummett, still disapprove: "You might as well read a cereal box."

What began with Hillegass's shipping summaries of Shakespeare's plays from the basement of his modest Lincoln, Neb., home—inspired by a friend who sold similar notes in Canada—is now a 60-employee business in an art-filled office building in Lincoln, offering a list of more than 220 literary titles. And Cliff himself, now 80 and suffering from Parkinson's disease, still serves as chairman of the board, though he no longer runs the daily operations. "He always said the employees make the company, and the notes belong to them," says wife Mary. Paraphrasing her husband, of course.