《资治通鉴·汉纪·汉纪三十七》
本年，北匈奴大举进攻云中郡。云中郡太守廉范进行抵抗。下属官员因本郡兵少，想要送信给邻郡请求救援，廉范不许。
是岁，北匈奴大入云中，云中太守廉范拒之；吏以众少，欲移书傍郡求救，范不许。
In this year, the Northern Xiongnu launched a massive attack on Yunzhong Commandery. Yunzhong Commandery Grand Administrator Lian Fan resisted. Subordinate officials wanted to send a message to neighboring commanderies for rescue because the commandery was short on troops, but Lian Fan denied the request.