An important part of doing any research is evaluating the sources you consult. Academic journal articles, technical and government reports, dissertations, conference proceedings, patents, standards, etc. are examples of such sources. Review journals, newspaper or magazine articles, encyclopedias, textbooks, tabular compilations, bibliographies, indexing and abstracting periodicals, dictionaries, and handbooks are all such sources. But the information is usually years out of date and are secondary sources of information - the result of someone else's research. Their usefulness lies primarily as sources of background information and for preliminary reading.
Encyclopedias sometimes publish yearbooks which attempt to update the information.
In the sciences, one series of encyclopedias stands out. The McGraw-Hill Encyclopedias listed below provide authoritative articles in all areas of the pure and applied sciences. They are an excellent place to start any research. McGraw-Hill Encyclopedia of Engineering. 1993 McGraw-Hill Encyclopedia of Science and Technology.