《水经注·卷十六》
也就是虞舜时代的大学上库和小学下库，夏禹时的大学东序和小学西序，殷商时的大学右学和小学左学，周朝时的大学东胶和小学虞库。
亦有虞氏之上庠、下庠，夏后氏之东序、西序，殷人之左学、右学，周人之东胶、虞庠。
That is, the upper ku of the university and the lower ku of the primary school in the era of Emperor Shun, the eastern xu of the university and the western xu of the primary school in the era of Yu the Great, the right xue the university and the left xue of the primary school in the Shang dynasty, and the eastern jiao of the university and the Yu ku of the primary school in the Zhou dynasty.