Lord was influenced by classical, blues and jazz but played his Hammond organ with a rock attitude and helped Deep Purple become pioneers of progressive and heavy rock.

BBC: Deep Purple's Jon Lord dies at 71

Holtzman returned to California with a suitcase full of cassettes of this unique, Farfisa-organ-driven psychedelic-rock sound that was forged during the Vietnam War, when American radio influenced traditional Cambodian styles.

NEWYORKER: Dengue Fever

Musically, Manzarek's spidery organ on "Light My Fire" is one of the most instantly recognizable sounds in rock history.

NPR: Manzarek, Founding Member Of The Doors, Dies At 74