According to the New Grove Dictionary of Music and Musicians, an "Electric bass guitar [is] a Guitar, usually with four heavy strings tuned E1'–A1'–D2–G2. " It also defines bass as "Bass (iv). A contraction of Double bass or Electric bass guitar. " According to some authors the proper term is "electric bass". Common names for the instrument are "bass guitar", "electric bass guitar", and "electric bass" and some authors claim that they are historically accurate.