الوصول الحر: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2015000800736Test
الوصول الحر: https://doaj.org/article/f2e58a7bc4614717afe5108524535c3aTest
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e810153ff7a17bad6ba6b3fb7c79d250Testhttp://europepmc.org/articles/PMC4541694Test