2002-18, Ancient Chinese Scientist (Set IV)《中国古代科学家》（第四组）
2002-18, Ancient Chinese Scientist (Set IV)《中国古代科学家》（第四组） Stamp Title: Ancient Chinese Scientist (Set IV) Scott No: 3226, 3227, 3228, 3229 Serial number: 2002-18 Values in set: 4 (4-1), Bian Que, 80 fen, 30*40 mm (4-2), Liu Hui, 80 fen, 30*40 mm (4-3), Su Song, 80 fen, 30*40 mm (4-4), Song Yingxing, 80 fen, 30*40 [...]