APA

Helsen P., Browne R. A., Anderson D. J., Verdyck P. & Van Dongen S. (2009). Galápagos Opuntia (prickly pear) cacti. : Botanical Journal of The Linnean Society of London.

Chicago

Helsen Phillippe, Browne Robert A, Anderson David J, Verdyck Peter and Van Dongen Stefan. 2009. Galápagos Opuntia (prickly pear) cacti. : Botanical Journal of The Linnean Society of London.

Harvard

Helsen P., Browne R. A., Anderson D. J., Verdyck P. and Van Dongen S. (2009). Galápagos Opuntia (prickly pear) cacti. : Botanical Journal of The Linnean Society of London.

MLA

Helsen Phillippe, Browne Robert A, Anderson David J, Verdyck Peter and Van Dongen Stefan. Galápagos Opuntia (prickly pear) cacti. : Botanical Journal of The Linnean Society of London. 2009.