In general not only in EU, you will find labor law, professions regulations, visa requirements and many other articles scattered in other sections affect mobility of labor from outside countries. 

Hi Eka, in an article I have published "I flussi migratori: Immigrazione in Europa: analisi della legislazione" you could fine some reference on relevant legislation, unfortunately the article is in Italian. I hope that can help

Article I flussi migratori: Immigrazione in Europa: analisi della legislazione

Oxford University Press has published a book Migrants at Work which focuses on the impact of migration, migration law and labour law; the editors are Cathryn Costello and Mark Freedland. The Human Rights of Migrants and Refugees in European Law is another publication which also examines international law on migration, human rights law  and refugee law in Europe. Humanitarian law may also apply in the current migration crisis in certain cases. For further details see www.rsc.ox.ac.uk/news