Monozygotic Twins (Identical Twins)
Here's your citation in American Psychological Association (APA) format:
Monozygotic Twins (Identical Twins). (n.d.). In Alleydog.com's online glossary. Retrieved from: https://www.alleydog.com/glossary/definition-cit.php?term=Monozygotic+Twins+%28Identical+Twins%29