When the work theory refers to sources and implements their classification, an autonomous source of labor law is examined that includes collective agreements. These are also professional sources because they are created by professional associations (trade unions and employers) as well as collective entities. Collective agreements are part of the legal rules regulating the subject of labor law. They are autonomous sources, but are sanctioned by organized government coercion. Their conclusion is mandatory where this is stipulated by the government, and among other things it defines the name, content, subjects, manner of conclusion, dispute resolution, etc. The collective agreement thus constitutes a written contract that regulates the rights and obligations of employees with the employer, and the rights and obligations of those same employers, in accordance with the law and other regulations. It is set for a definite or indefinite period of time, and it contains legal rules and based on them the individual acts on the creation of the rights, obligations and responsibilities of the employee with the employer are created.