الإتاحة: https://doi.org/10.1046/j.1523-1747.1999.00525.xTesthttps://api.elsevier.com/content/article/PII:S0022202X15404300?httpAccept=text/plainTesthttps://api.elsevier.com/content/article/PII:S0022202X15404300?httpAccept=text/xmlTest
الإتاحة: https://doi.org/10.1067/mjd.2000.101883Testhttps://api.elsevier.com/content/article/PII:S0190962200194848?httpAccept=text/xmlTesthttps://api.elsevier.com/content/article/PII:S0190962200194848?httpAccept=text/plainTest
الإتاحة: https://doi.org/10.1007/s001050050376Test