Wojtusik, Jessye, Isabelle Brandicourt, Wendy Rice, and Terri Roth. 2020. “Reproductive Cycle and Pregnancy Monitoring in the Common Hippopotamus (Hippopotamus Amphibius) through Salivary Steroid Analyses and Trans-Abdominal Ultrasonography”. Journal of Zoo and Aquarium Research 8 (3):181-87. https://doi.org/10.19227/jzar.v8i3.494.