Secondary source

Definition

An account written later by someone analysing the past, such as a textbook or scholarly book. It interprets primary sources and may change as research develops, which is why two books on the same topic can differ. A responsible reader checks the author's evidence, notes the date of publication and compares more than one account. Scholarly databases of voyages are a hybrid, compiled from primary records. See also: primary source, historiography, and the guide Historiography and Why the Numbers Are Debated.