Quarteto em Cy (a play on words of the Portuguese for 'Quartet in B' by poet and lyricist Vinicius de Moraes) is a quartet of sisters from the Tropicalia musical movement in Brazil. They first became known for their collaborations with Vinicius de Moraes, and later worked with a number of other composers from the movement. They are Cybele, Cylene, Cynara, and Cyva.

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