Photo taken on Sept. 7, 2022 shows a set of four commemorative stamps themed "Modern Chinese Scientists (Group 9)." Chinese geologist Liu Dongsheng, physicist Cheng Kaijia, mathematician Wu Wenjun and agronomist Yuan Longping are chosen as portraits on the stamps. (Xinhua/Wang Xiang)

China Association for Science and Technology and China Post on Wednesday in Beijing jointly released a set of four commemorative stamps themed "Modern Chinese Scientists (Group 9)."

Chinese geologist Liu Dongsheng, physicist Cheng Kaijia, mathematician Wu Wenjun and agronomist Yuan Longping are chosen as portraits on the stamps.

Nine groups of commemorative stamps have been released so far since the series was first issued in 1988, and 38 modern Chinese scientists have been selected as portraits, including geologist Li Siguang, meteorologist and geographer Zhu Kezhen and opticist Wang Daheng.