I don't have suggestions for books, but have this suggestion: write web-based 'software as a service' (SAAS) that you host yourself. That way, clients don't see the source code so to pinch your ideas they would have to reverse-engineer the thing from the UI's. The world is moving in this direction - and it is a nicer business model for software-makers - you can gain an awful lot of insight from analysing the behaviour of the clients using your applications - which then influences your development roadmap.
SAAS works well if there is enough documentation and help for the clients to set up themselves (so you don't have to send people in to do setup - a big resource drain for you), it must be intuitive enough that they can get going without too much training, and the payment (usually subscription by credit card) is easy.
Updates are easier - rather than having to worry about supporting dozens or hundreds of customers with the software installed on their servers, you just update the web-application and everybody gets the update. This cuts down on tech support issues.
By providing a web-based app, you can integrate support via an online portal, where you put them through an automated 'is your query in the FAQ' bit first. If done well, this can reduce your tech support burden a lot.
Marketing is easier too - you just let people open up trial accounts that expire in 20 days or something - it doesn't cost you anything and it reduces the barrier to getting the product into customers' hands. Getting them to try it out is the hardest bit - if the application works well then the rest should be plain sailing.
What else... ah - cross selling - getting them to interact with your web-app means you can get their attention easily - when you have developed a new app that you think they might be interested in, especially if it is related to the app they are using, tell them about it via the app they already use every day.
There are more advantages of web-based SAAS I'm sure, like easy licensing model (whilst they pay their subscription, you keep their app account going...), easier features-based upgrade paths etc etc.