《资治通鉴·唐纪·唐纪五十一》
翰林学士郑上奏说： 根据惯例，只有封拜王位、任命宰相才使用白麻纸，现在要用白麻纸任命护军中尉，不知陛下这是特别以此宠任窦文场呢，还是就此便成为定式呢？ 
翰林学士郑絪奏言： 故事惟封王、命相用白麻，今以命中尉，不识陛下特以宠文场邪，遂为著令也？ 
Imperial scholar Zheng said: According to protocol, white hemp paper is used only for enfeoffment as a king or appointment as prime minister. Now, with this use of white hemp paper to appoint a lieutenant general of the guard, is this Your Majesty especially favoritism towards Dou Wenchang, or is this to be the new standard?