Detailed information can be found on the All-China Association of Agents. There are many firms here in Chengdu, but there are basically 2 with patent practice qualifications. The bigger ones are Jiuding, Hongqiao and Hangzhou, while Tiance and Chaofan are mainly trademarks. As far as agents are concerned, there are not many certificates in Chengdu, and there are relatively more big ones, and there may be three or four other small ones. You can check the details directly on the website of the All-China Association of Agents.