document: ITIS & Species 2000 Catalogue of Life Management Hierarchy; M. Ruggiero & D. Gordon, eds. 2011. Consensus Management Hierarchy for the ITIS & Species2000 Catalogue of Life. Contributors: Nicolas Bailly, Thierry Bourgoin, Richard Brusca, Thomas Cavalier-Smith, Daphne Fautin, Dennis Gordon, Gerald Guala, Michael Guiry, Paul Kirk, Elliot Lefkowitz, David Mabberly, David Maddison, Alan Paton, Michael Ruggiero, Peter Stevens, and Brian Tyndall
website: Angiosperm Phylogeny Website, 2012; Angiosperm Phylogeny Website, botanical information system at the Missouri Botanical Garden, available at http://www.mobot.org/MOBOT/research/APweb/
database: The PLANTS Database; National Plant Data Center, NRCS, USDA. Baton Rouge, LA 70874-4490 USA. http://plants.usda.gov
database: The PLANTS Database; National Plant Data Center, NRCS, USDA. Baton Rouge, LA 70874-4490 USA. http://plants.usda.gov