《后汉书·列传·张曹郑列传》
当时郑玄年已六十，他的学生从遥远的地方来的如河内人赵商等，计有几千人。
时年六十，弟子河内赵商等自远方至者数千。
At that time, Zheng Xuan was already sixty years old, and his students came from far and wide, like Zhao Shang of Hanoi, and there were several thousand of them together.