Books on Consulting

I haven't received any recommendations for Books for Artists or on Non-profit Management, but these books were championed for Consulting:

• The Business of Consulting: The Basics and Beyond by Elaine Biech
• The Consultant's Toolkit: High-Impact Questionnaires, Activities and How-to Guides for Diagnosing and Solving Client Problems by Mel Silberman
• The Consultant's Quick Start Guide: An Action Plan for Your First Year in Business by Elaine Biech
• Consulting For Dummies by Bob Nelson and Peter Economy
• The Contract and Fee-Setting Guide for Consultants and Professionals by Howard L. Shenson
• Flawless Consulting: A Guide to Getting Your Expertise Used by Peter Block
• Free Agent Nation: The Future of Working for Yourself by Daniel H. Pink
• Getting Started in Consulting by Alan Weiss
• How to Build a Successful Consulting Practice by Jack Phillips
  
• The Independent Consultant's Q & A Book by Lawrence W. Tuller
• The McKinsey Mind: Understanding and Implementing the Problem-Solving Tools and Management Techniques of the World's Top Strategic Consulting Firm by Ethan M. Rasiel
• Perspectives on Strategy from The Boston Consulting Group by Carl W. Stern
• Persuasive Business Proposals: Writing to Win Customers, Clients, and Contracts by Tom Sant
• Value-Based Fees: How to Charge and GetWhat You're Worth by Alan Weiss

Thoughts?

The list is a little overwhelming and I'd like to pare it down to the essentials.