Ghavidel-Syooki,M , and Borji,S . "Chronostratigrahy of Acritarchs and Chitinozoans from upper Ordovician Strata from the Robat-e Gharabil Area, NE Alborz Mountains, Northern Khorassan Province: Stratigraphic and Paleogeographic Implications", Journal of Sciences, Islamic Republic of Iran, 29, 1, 2018, 35-51. doi: 10.22059/jsciences.2018.64793