《元史·列传·卷八十三》
乃穿上礼服向北再拜，也自缢而死。郑玉字子美，徽州歙县人，年幼聪明好学，深悉六经，尤精于春秋。无意做官而勤于教学，学子门人前来求学的很多，以致房子容不下，有的学生便在他的住处旁就地建造 师山书院 作为课堂宿舍。
幼敏悟嗜学，既长，覃思《六经》，尤邃于《春秋》，绝意仕进，而勤于教。学者门人受业者众，所居至不能容。学者相与即其地构师山书院以处焉。
He put on his official uniform, knelt and bowed north, and also hanged himself. Zheng Yu, courtesy name Ziming, was a native of Shexian, Huizhou. He was intelligent and fond of studying from a young age. He was proficient in the Six Classics, especially in the Spring and Autumn Annals. He had no intention of becoming an official but was diligent in teaching. There were many students who came to him to study, so many that his house could not accommodate them, and some students built the Shi Shan Academy next to his residence as a classroom and dormitory.