الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3988d976056ecee6ff01773534c2929fTesthttp://www.sciencedirect.com/science/article/pii/S0104001420302037Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dd14da1a5f04891c6dd9f6fba6a9ea3eTesthttp://www.sciencedirect.com/science/article/pii/S010400142030052XTest
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ee5bbc4d7e15f19a035be0d1b49679c0Test