From the ARE 5.0 Handbook:
-The Architect’s Handbook of Professional Practice The American Institute of Architects John Wiley & Sons, 14th edition (2008) and 15th edition (2014)
-2018 Code of Ethics and Professional Conduct AIA Office of General Counsel The American Institute of Architects, 2018
-Legislative Guidelines and Model Law/Model Regulations National Council of Architectural Registration Boards 2018-2019
-Model Rules of Conduct National Council of Architectural Registration Boards 2018-2019
Law for Architects : Robert Hermann
Professional Practice: A Guide to Turning Designs into Buildings
Architect | Entrepreneur : A Field Guide by Eric Reinholdt <Has a good breakdown of the business types.
A lot of these books can get expensive, so check with your firm to see if they will buy the book, check with your local AIA Chapter, and Library System. I’ll look for more resources in the next few days and please share anything you’ve found on your own.