^Merriam-Webster Dictionary entry on hip-hop, retrieved from merriam-webster.com: A subculture especially of inner-city youths who are typically devotees of rap music; the stylized rhythmic music that commonly accompanies rap; also rap together with this music.
^ abcdEncyclopædia Britannica article on rap, retrieved from britannica.com: Rap, musical style in which rhythmic and/or rhyming speech is chanted (“rapped”) to musical accompaniment. This backing music, which can include digital sampling (music and sounds extracted from other recordings), is also called hip-hop, the name used to refer to a broader cultural movement that includes rap, deejaying (turntable manipulation), graffiti painting, and break dancing.
^Encyclopædia Britannica article on hip-hop, retrieved from britannica.com: Hip-hop, cultural movement that attained widespread popularity in the 1980s and ’90s; also, the backing music for rap, the musical style incorporating rhythmic and/or rhyming speech that became the movement’s most lasting and influential art form.
^Kugelberg, Johan (2007). Born in the Bronx. New York: Oxford University Press. p. 17. ISBN 978-0-7893-1540-3.
^Harvard Dictionary of Music article for hip hop, retrieved from Google Books: While often used to refer to rap music, hip hop more properly denotes the practice of entire subculture
^AllMusic article for Hip-hop/Urban, retrieved from AllMusic.com[dead link]: Hip-Hop is the catch-all term for rap and the culture it spawned.