Summerfield, G. (1968). Voices: The first book. Penguin.
Cita Chicago Style (17a ed.)Summerfield, Geoffrey. Voices: The First Book. Harmondsworth: Penguin, 1968.
Cita MLA (8a ed.)Summerfield, Geoffrey. Voices: The First Book. Penguin, 1968.
Precaución: Estas citas no son 100% exactas.