الوصول الحر: https://doaj.org/article/ef638e1c65a74d319ac6f23a34ca94f2Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::343cad1e39f5d5e9f56ce4bf8d520a26Testhttps://hdl.handle.net/20.500.12636/987Test
الإتاحة: https://doi.org/10.1140/epjst/e2019-900045-4Testhttps://hdl.handle.net/11391/1550676Test