الوصول الحر: https://doaj.org/article/29224abeb3c646a191ab3af17531b3e6Test
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1cac6e68619ea2d97e1e3ac0e117d1b5Testhttps://vniigis.elpub.ru/jour/article/view/512Test