I am aware of 2 books that may help you:
Choosing and Using a Consultant by Herman Holtz published by John Wiley and Sons. ISBN: 0-471-60287-6
How to Select and Use Consultants:a clients guide by Milan Kuber. Pub. by International Labour Office, ISDN:92-2-10851-1
Hope this helps. Good luck with your thesis.
Rgds
Ian Tomisson