Help keep it up there--if not higher. Get a copy from your local Amazon Kindle outlet (yes I understand people being against Amazon, but one reason it succeeds is that publishing a book via Kindle is so much easier than any other method):
Here are the Kindle links:
It's also #4 in microeconomics--because I also show the real profit maximizing formula for real world firms, and it has nothing to do with equating marginal cost and marginal revenue.