Cita APA (7a ed.)

Koch, H. L. (1967). Twins and twin relations (2. print.). Univ. of Chicago Pr.

Cita Chicago Style (17a ed.)

Koch, Helen L. Twins and Twin Relations. 2. print. Chicago, Ill. [u.a.]: Univ. of Chicago Pr, 1967.

Cita MLA (9a ed.)

Koch, Helen L. Twins and Twin Relations. 2. print. Univ. of Chicago Pr, 1967.