الوصول الحر: https://doaj.org/article/d899c3209ac54ab1b435e3d0db5487f1Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2c58b0d65e34a71180be9008bb73956aTesthttp://www.pagepress.org/journals/index.php/or/article/view/4583Test