Seven abbreviations of nouns

China's first official catalogue and the first bibliography book. Liu Xin, a scholar, astronomer and bibliographer of the Western Han Dynasty, was compiled in 6-5 BC, which is the new general catalogue of school-based books of the government. First, in 26 BC, Liu Ao, Emperor Wu of the Han Dynasty, ordered Dr. Guanglu Liu Xiang to lead the book proofreading work in the imperial court: Liu Xiang passed on poems and essays of various schools, served as a captain of infantry, and Taishi ordered Yin Xian to proofread mathematics and serve Li. Once the revised edition is completed, Liu Xiang will write a narrative and play it with the book. After Liu Xiang recorded it, he compiled Bielu, a total of 20 volumes. Liu Xiang died in 6 BC. Liu Xin, the Emperor of the Han Dynasty, ordered Liu Xin to follow in his father's footsteps, and concentrated his new learning on Tianlu Pavilion, which was fully incorporated into Seven Laws.