Chatchalerm Ketwetsuriya และ Pitsanupong Kanjanapayont. (2016) Stratigraphic Distribution of Permian Gastropods from Tak Fa Formation in Southern Part of Nakhon Sawan Province, Thailand. <i>Bulletin of Earth Sciences of Thailand (BEST)</i>, <i>8</i>(1), 88-92.Chatchalerm Ketwetsuriya และ Pitsanupong Kanjanapayont. "Stratigraphic Distribution of Permian Gastropods from Tak Fa Formation in Southern Part of Nakhon Sawan Province, Thailand". Bulletin of Earth Sciences of Thailand (BEST) 8 (2016):88-92.Chatchalerm Ketwetsuriya และ Pitsanupong Kanjanapayont. Stratigraphic Distribution of Permian Gastropods from Tak Fa Formation in Southern Part of Nakhon Sawan Province, Thailand. Department of Geology, Chulalongkorn University:ม.ป.ท. 2016.