الإتاحة: https://doi.org/10.1016/j.joca.2019.02.129Testhttps://api.elsevier.com/content/article/PII:S1063458419301712?httpAccept=text/xmlTesthttps://api.elsevier.com/content/article/PII:S1063458419301712?httpAccept=text/plainTest
الإتاحة: https://doi.org/10.1016/j.joca.2019.02.681Testhttps://api.elsevier.com/content/article/PII:S1063458419307241?httpAccept=text/xmlTesthttps://api.elsevier.com/content/article/PII:S1063458419307241?httpAccept=text/plainTest