Generally speaking, you can ask the meeting group for the proof of the meeting you voted for, or you can go to your school library and quote the author's name of your paper topic, so that the library can verify whether the paper has been retrieved and issue a certificate for you. Of course, retrieval is also divided into SCI retrieval, EI retrieval and ISTP retrieval. These three databases are different. If it is EI search, you can go to EI Academic Conference Center. There is an EI search portal and detailed EI conference learning materials.