Purves WK, Sadava DE, Orians GH, Heller HC, Life: The Science of Biology, Macmillan, 2000, p. 736, ISBN 978-0-7167-3873-2. URL consultato il 23 marzo 2018 (archiviato dall'url originale il 26 giugno 2019).
«A single body can function as both male and female. Sexual reproduction requires both male and female haploid gametes. In most species, these gametes are produced by individuals that are either male or female. Species that have male and female members are called dioecious (from the Greek for 'two houses'). In some species, a single individual may possess both female and male reproductive systems. Such species are called monoecious ("one house") or hermaphroditic.»
