There are bunches of books on the market for lawyers interested in marketing their practices. Many are published by the American Bar Association. There are other publishers in the game as well.
They cover everything from the basics of opening a practice and generating initial clients to more advanced volumes dealing with advertising, networking, and social media.
Should you buy them?
Sadly, most of these books have two strikes against them.
First, they're often sold for a premium price. A similar book sold to business professionals might sell for one-quarter of the price or less.
Second, these books often aren't very good. The really good authors focus on larger markets. For instance, you won't find Seth Godin writing specifically for lawyers. The same is true of most other successful writers on marketing, management, and business topics. The lawyer book authors tend to be lawyers who haven't done much marketing, and their writing isn't particularly insightful. It's unfortunate.
Most of the time, I find books aimed at the business market much more interesting and useful than those aimed at lawyers. I've found books like Small Business Marketing for Dummies much more helpful than the corresponding volume written for lawyers. Seriously, it's a sad day when books aimed at dummies are better than books aimed at lawyers. It's even worse when the lawyer book costs much, much more than the Dummies volume.
If you buy the non-lawyer books, you'll likely find yourself making some decisions about how to apply what you learn to your particular business. That's what all business owners have to do: they have to think about what will work in their industry. That exercise—the thinking—is good for you. It keeps your marketing fresh and interesting. It forces you to step away from a formulaic approach and develop marketing that is unique to you. That's a good thing.
I stay away from the lawyer-focused books. I read all the time, and I find much more value in the wealth of material coming out of the authors focused on business. There's good stuff out there. It just isn't usually the stuff written for us.