8 7 ) ▁a ▁group ▁focused ▁on ▁H ip ▁Hop , ▁R & B , ▁Mot own ▁and ▁Soul ▁music . ▁T alis man ▁( f . ▁ 1 9 8 9 ): ▁a ▁group ▁with ▁roots ▁in ▁music ▁from ▁South ▁Africa ▁and ▁the ▁African ▁di as por a . ▁Harm on ics ▁( f . ▁ 1 9 9 1 ): ▁an ▁alternative ▁rock - f oc used ▁group ▁known ▁for ▁their ▁highly ▁produced ▁record ings . ▁Test im ony ▁( f . ▁ 1 9 9 1 ): ▁a ▁Christian ▁music ▁a ▁c app ella ▁group . ▁Ra ag ap ella ▁( f . ▁ 2 0 0 2 ): ▁a ▁co - ed ▁a ▁c app ella ▁group ▁with ▁a ▁South ▁Asian ▁focus . ▁O - T one ▁( f . ▁ 2 0 1 6 ): ▁a ▁group ▁with ▁a ▁focus ▁on ▁East ▁Asian ▁music . ▁ ▁Bibli ography ▁▁ ▁Bro cken br ough , ▁Andy ▁( 2 6 ▁September ▁ 1 9 9 1 ). ▁" A ▁time ▁to ▁sing ▁and ▁sing ▁and ..." ▁published ▁in ▁The ▁Stan ford ▁Daily , ▁p .   8 . ▁Print . ▁ ▁Ch op ra , ▁N it in ▁( 2 4 ▁September ▁ 1 9 9 8 ). ▁" A ▁c app ella ▁nation : ▁A ▁Stan ford ▁tradition ," ▁published ▁in ▁The ▁Stan ford ▁Daily : ▁Inter mission , ▁pp .   5 – 7 . ▁Print . ▁ ▁O mer , ▁Iss ra ▁( 1 1 ▁August ▁