1. Association of Zoos and Aquariums (2019). The economic impact of spending for operations and construction by AZA members in 2018. Available at: https://www.aza.org/economic-impact-reports.
2. Association of Zoos and Aquariums (2021). Annual report on conservation and science. Available at: https://www.aza.org/annual-report-on-conservation-and-science.
3. Sixty years of collection planning: What species do zoos and aquariums keep?;Brereton;International Zoo Yearbook,2020
4. The practical difficulties and financial implications of endangered species breeding programmes;Conway;International Zoo Yearbook,1986
5. Why zoos & aquariums matter: Assessing the impact of a visit to a zoo or aquarium;Falk,2007