1. What Is Biodiversity; Connexions, Houston, TX, USAhttp://cnx.org/content/col10639/1.1/
2. IUCN Red List Version 2019-2: Table 1a: Number of Species Evaluated in Relation Overall Number Described Species, and Numbers of Threatened Species by Majpr Groups of Organisms; Cambridge, UKhttps://nc.iucnredlist.org/redlist/content/attachment_files/2019_2_RL_Table_1a_v2.pdf
3. Importance of pollinators in changing landscapes for world crops
4. The Assessment Report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on Pollinators, Pollination and Food Production; Secretariat of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Bonn, Germanyhttps://www.ipbes.net/sites/default/files/downloads/pdf/individual_chapters_pollination_20170305.pdf
5. Bee declines driven by combined stress from parasites, pesticides, and lack of flowers