الإتاحة: https://digitalcommons.unmc.edu/com_gcba_articles/29Testhttps://digitalcommons.unmc.edu/cgi/viewcontent.cgi?article=1028&context=com_gcba_articlesTest
الإتاحة: https://kramerius.lib.cas.cz/view/uuid:0554a1fe-db29-4723-952e-83003d4ee783Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=od______2186::7a7980e5f43fef428606be0e90b8a472Testhttp://www.nusl.cz/ntk/nusl-438093Test
الإتاحة: https://doi.org/20.500.11956/124700Testhttps://hdl.handle.net/20.500.11956/124700Test