الوصول الحر: https://doaj.org/article/f7644296069f46d9a42a82560decf7dcTest
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c9afeba8b7e5c6d91c6603e968412e2eTesthttps://doi.org/10.2478/s11536-010-0010-0Test