They are responsible for all the neat aspects of the book. I am very pleased with the way it has turned out, even though there are many things I would do differently the next time. As I said, the ideal method is to design the book to be interactive from the very beginning. The venue for the production included a Hollywood sound stage, the Voyager offices in Long Beach and New York, and a sound studio at Apple Computer. I don't believe that an individual could do the whole thing.
Articles are relatively easy for an individual to write.
Books are difficult. To do a credible job of producing an interactive, multimedia product is probably beyond the expertise of most individuals. Any virtues come at a high price. My exam questions. My introductory lecture.