APA-viite (7. p.)

Penn, H. (2000). Early childhood services: Theory, policy, and practice. Open University Press.

Chicago-viite (17. p.)

Penn, Helen. Early Childhood Services: Theory, Policy, and Practice. Buckingham, [Eng.]: Open University Press, 2000.

MLA-viite (9. p.)

Penn, Helen. Early Childhood Services: Theory, Policy, and Practice. Open University Press, 2000.