2 books, summarised simply.
Regulatory Hacking
by Evan Burfield
By Evan Burfield, step-by-step textbook with case studies for startups entering regulated markets.
Legal Guide for Starting & Running a Small Business
by Fred S. Steingold
By Fred S. Steingold (Nolo Press, multiple editions), this is a practical reference covering the everyday legal basics small business owners need: choosing a business structure, contracts, employment law, leases, and liability.