Chronicles of the Three Kingdoms: Chapter 3 of The Book of Wei: 
An Overview of The History of Wei lists Lang and Kong Gui in the "Favored Male Courtiers" section 2. He went by the moniker of Shulin. He was a native of Tianshui. At the beginning of the Jian An era, the general Yang Qiu had a mandate from the founding king (Cao Cao) and the king gave Gui the position of cavalry commander. Gui, by nature was law-abiding , and knew how to play chess...
Cao Cao loved him. He was always at the king's side. He followed the king's going out and coming in. Gui paid close attention to the king's desires and good moods. Because he could make speeches explaining the details of a matter clearly, most of his undertakings went smoothly, and he received many rewards. Many people gave him gifts, thus he was always dressed like a duke and ate on jade plates. Not only did the founding king loved Gui, the courtiers, military officers and nobles all sought good relations with him.