Baidu Encyclopedia: This is the largest online Chinese encyclopedia in China, which contains a large number of Chinese terms, including people, science and technology, history, culture and other aspects.
Encyclopedia Britannica Online: This is a paid online encyclopedia in English. It is famous for its high-quality articles, pictures and videos, covering science, technology, humanities and other fields.
Google Academic: This is a free academic search engine, which will search relevant information in academic publications and provide reading links.
CNKI: This is a general repository of knowledge resources in China for a fee, including papers, periodicals, patents, dissertations and so on, covering natural science, social science and other fields.