shohani,N. , , Shouhani,M. , and shohani,S. . "Analysis of Relationship and Role of Migration (Village-City) in the Formation and Expansion of Informal Occupations (Case study: Ilam city)", a scientific journal of ilam culture, 20, 64.65, 2020, 120-149. doi: 10.22034/farhang.2020.106813