1. Posttoday, Pet business for aging society, https://www.posttoday.com/economy/news/540479 (2018)
2. Niall McCarthy, Which Countries Have The Most Cat Owners?, https://www.statista.com/chart/10267/which-countries-have-the-most-cat-owners (2017)
3. Neilson J.C., AAFP-AAHA Feline life stage guidelines, Journal of Veterinary Medicine. 104 (2009)
4. Dabritz H.A., Conrad P.A., Serological prevalence of Toxoplasma gondii infection in cats (Belém, Pará, Brazil), Zoonoses and Public Health 57 (2010)
5. Virta R.L., Mineral Commodity Summaries 2005, Clays: U.S. Geological Survey Mineral Commodity Summaries (United States, 2005)