《旧唐书·列传·卷一百三十九》
国子祭酒徐克开堂讲经，凭借位尊纵论，众人没有敢于交锋的，只有德明与他抗衡论争，全朝人对他赞叹不已。
国子祭酒徐克开讲，恃贵纵辨，众莫敢当；德明独与抗对，合朝赏叹。
The president of the Imperial College, Xu Ke, gave a lecture. Because he was in a high position, no one dared to debate him. Only Deming competed with him, and all the imperial officials praised him.