Παραπομπή APA

Hal Markowitz. (1982). Behavioral enrichment in the zoo. Newyork.

Παραπομπή Chicago Style

Hal Markowitz. Behavioral Enrichment in the Zoo. Newyork, 1982.

Παραπομπή MLA

Hal Markowitz. Behavioral Enrichment in the Zoo. Newyork, 1982.