"Pollination and Bee Plants"(PDF). 1998. Archived from the original(PDF) on 30 September 2007. Retrieved 31 October 2018. Excerpted from Beekeeper's Handbook, Sammataro/Avitabile
Purdy, Elizabeth (2012). "Ecosystems". In S. George Philander (ed.). Encyclopedia of Global Warming & Climate Change. Vol. 1 (2nd ed.). Thousand Oaks, CA: SAGE Reference. pp. 485–487. doi:10.4135/9781452218564. ISBN978-1-4129-9261-9.
Lotze, Heike K.; Milewski, Inka (October 2004). "Two Centuries of Multiple Human Impacts and Successive Changes in a North Atlantic Food Web". Ecological Applications. 14 (5): 1428–1447. doi:10.1890/03-5027. ISSN1051-0761.
galegroup.com
go.galegroup.com
Brenda Wilmoth Lerner; K. Lee Lerner, eds. (2009). "Ecosystems". Environmental Science: In context. In Context Series. Vol. 1. Detroit: Gale. pp. 242–246. ISBN978-1-4103-3754-2. OCLC277051356.
Purdy, Elizabeth (2012). "Ecosystems". In S. George Philander (ed.). Encyclopedia of Global Warming & Climate Change. Vol. 1 (2nd ed.). Thousand Oaks, CA: SAGE Reference. pp. 485–487. doi:10.4135/9781452218564. ISBN978-1-4129-9261-9.
"Pollination and Bee Plants"(PDF). 1998. Archived from the original(PDF) on 30 September 2007. Retrieved 31 October 2018. Excerpted from Beekeeper's Handbook, Sammataro/Avitabile
worldcat.org
Brenda Wilmoth Lerner; K. Lee Lerner, eds. (2009). "Ecosystems". Environmental Science: In context. In Context Series. Vol. 1. Detroit: Gale. pp. 242–246. ISBN978-1-4103-3754-2. OCLC277051356.
Lotze, Heike K.; Milewski, Inka (October 2004). "Two Centuries of Multiple Human Impacts and Successive Changes in a North Atlantic Food Web". Ecological Applications. 14 (5): 1428–1447. doi:10.1890/03-5027. ISSN1051-0761.