Hinrichs, Katrin (2011). "Nuclear Transfer". In McKinnon, Angus O.; Squires, Edward L.; Vaala, Wendy E.; Varner, Dickson D. (eds.). Equine Reproduction. John Wiley & Sons. pp. 2924–2930. ISBN978-0-470-96187-2.
Liberatore, Katie L.; Jiang, Ke; Zamir, Dani; Lippman, Zachary B. (2013). "Heterosis: The Case for Single-Gene Overdominance". Polyploid and Hybrid Genomics. pp. 137–152. doi:10.1002/9781118552872.ch8. ISBN978-0-470-96037-0.
Wang, Xisheng; Bou, Gerelchimeg; Zhang, Xinzhuang; Tao, Li; Shen, Yingchao; Na, Riga; Liu, Guiqin; Ren, Hong; Ren, Xiujuan; Song, Lianjie; Su, Shaofeng; Bai, Dongyi; Zhao, Yiping; Li, Bei; Dugarjaviin, Manglai (July 2021). "A Fast PCR Test for the Simultaneous Identification of Species and Gender in Horses, Donkeys, Mules and Hinnies". Journal of Equine Veterinary Science. 102: 103458. doi:10.1016/j.jevs.2021.103458. PMID34119210.
Camillo, Francesco; Rota, Alessandra; Biagini, Lorenzo; Tesi, Matteo; Fanelli, Diana; Panzani, Duccio (June 2018). "The Current Situation and Trend of Donkey Industry in Europe". Journal of Equine Veterinary Science. 65: 44–49. doi:10.1016/j.jevs.2017.11.008. hdl:11568/905165.
Camillo, Francesco; Rota, Alessandra; Biagini, Lorenzo; Tesi, Matteo; Fanelli, Diana; Panzani, Duccio (June 2018). "The Current Situation and Trend of Donkey Industry in Europe". Journal of Equine Veterinary Science. 65: 44–49. doi:10.1016/j.jevs.2017.11.008. hdl:11568/905165.
Wang, Xisheng; Bou, Gerelchimeg; Zhang, Xinzhuang; Tao, Li; Shen, Yingchao; Na, Riga; Liu, Guiqin; Ren, Hong; Ren, Xiujuan; Song, Lianjie; Su, Shaofeng; Bai, Dongyi; Zhao, Yiping; Li, Bei; Dugarjaviin, Manglai (July 2021). "A Fast PCR Test for the Simultaneous Identification of Species and Gender in Horses, Donkeys, Mules and Hinnies". Journal of Equine Veterinary Science. 102: 103458. doi:10.1016/j.jevs.2021.103458. PMID34119210.
One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Mule". Encyclopædia Britannica. Vol. 18 (11th ed.). Cambridge University Press. pp. 959–960.