Petrova, Nadya, Elena Hristova, Marina Hristova, and Plamen Todorov. “Investigating the Relationship Between the Day of Embryo Freezing and Pregnancy Rates”. Proceedings of the Bulgarian Academy of Sciences 75, no. 12 (December 23, 2022): 1749–1756. Accessed September 8, 2024. https://proceedings.bas.bg/index.php/cr/article/view/214.