https://www.noormags.ir ar https://www.noormags.ir/view/ar/articlepage/3066730/potential-pollution-factors-of-karst-water-resources-in-the-karde-basin-north-of-mashhad-county-the-necessity-of-management-and-protection-of-karst-water-resources Mon, 22 Sep 2003 20:30:00 GMT