You wrote, "for now it's too early to specialize in just one". That's the opposite of commonly recommended strategy. You specialize when you start out, not la

You wrote, "for now it's too early to specialize in just one". That's the opposite of commonly recommended strategy. You specialize when you start out, not later on. You diversify when you have some amount of success. Anyway, to answer your original question: go to a bookstore. Contact the author directly with your offer. It's possible the author will have the rights to put the content into an iPhone app. Even if he doesn't, he's probably got lots of other content that hasn't been published. If you want to think bigger, contact the publisher directly. They have lots of authors and you may be able to negotiate a deal. Alternatively, look at websites, blogs and such. Contact those authors.