Collective bargaining consists of negotiations between an employer and a group of employees so as to determine the conditions of employment. The result of collective bargaining procedures is a collective agreement. Employees are often represented in bargaining by a union or other labor organization. Collective bargaining is governed by federal and state statutory laws, administrative agency regulations, and judicial decisions. In areas where federal and state law overlap, state laws are preempted. See, U.S. Constitution, Art. VI.
(From the Legal Information Institute)
Here are selected books on Collective Bargaining from the RUL collection.