الإتاحة: https://doi.org/10.1186/1745-6215-13-201Testhttps://doaj.org/article/afad13cebdc1427984d54bd3dd232e45Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::cb987e89f75f95ee0536555d2369b845Testhttp://europepmc.org/articles/PMC6336748Test
الإتاحة: http://www.trialsjournal.com/content/13/1/201Test