Sources

https://www.encyclopedia.com/science-and-technology/biology-and-genetics/genetics-and-genetic-engineering/hybrid

10 Most Unbelievable Hybrid Animals.

https://www.boredpanda.com/strange-hybrid-animals-that-are-hard-to-believe-actually-exist/

https://hybridanimalsbiologywebsite.weebly.com/types-and-history.html

http://www.slate.com/news-and-politics/2018/04/michigan-state-youth-volleyball-coach-rick-butler.html

https://motherboard.vice.com/en_us/article/ezp5da/this-is-why-ligers-mules-and-other-hybrid-animals-cant-reproduce

https://www.nytimes.com/2002/07/09/science/crossbreeding-to-save-species-and-create-new-ones