Other forms: encyclopedias
An encyclopedia is a reference work designed to cover all branches and topics of knowledge. We might describe someone who seems to know everything as a "walking encyclopedia."
Encyclopedia comes the Greek words for "comprehensive" (cyclo) and "education" (pedia). The first encyclopedias were books (usually in many volumes), but now we have online and electronic encyclopedias. This reference is usually organized alphabetically and covers as many topics as possible. If you're doing research, the encyclopedia is a good place to start.