الوصول الحر: https://doaj.org/article/afc6de6e958a4c9bb0ebc806ab2e5fbbTest
الوصول الحر: https://doaj.org/article/5805ee09aa7744aab9f1857fae701e70Test
الإتاحة: https://doi.org/10.3390/min9010005Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b4e45c5d1777a20b1d56aa6c21df3df5Testhttp://www.sciencedirect.com/science/article/pii/S1876380420601057Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f17ea569a4e57b7e196f82f65d274189Test